For an issue like this, it doesn't work to simply do an exercise that supposedly works the muscle. Even if the muscle is the limiting link in the lift, if your body isn't using it, it won't get stronger. For example, my mid-upper-back was lax because of typical nerd posture. Even though it limited my squat, years of squatting didn't force those muscles to do anything. I just had a really weak squat that relied on other muscles compensating. Then one day I ran across a suggestion to do bat wings and hold at the top for 20-30 seconds, and I became close friends with some muscles in my back that I barely knew existed.
A web site showing you how to discover each muscle or muscle group in your body (bat wings for deep mid-back, glute bridge for glutes, etc.) would be AMAZING, and I bet people would get referred there all the time from places like r/Fitness where people go for advice.
For me personally, one of those postural imbalances turned into an injury (shoulder), and I found doing exercises that targeted a very specific muscle (infraspinatus) really helped in my recovery.
I think everyone could benefit from spending some time exploring their body by targeting muscles that may be easy to ignore in larger compound movements, if only for bringing awareness to them (which should benefit the main movements in the long run by making them more efficient).
Yoga definitely is great and I practice asana 5x per week. I will say that my injury came up during an asana class, though, and it wasn't until I really targeted my weak scapular muscle groups that it got better.
Something like that would seem useful to a lot of lower-mid weightlifters who don't have a real lifting coach.
I couldn't get back on the bike without knee pain for months. Now I am totally out of shape. I could go to PT, as I was given a referral, but it's expensive, and I prefer self-help resources.
There's a lot of benefit to finding someone that teaches you both what to do and how to do it, and is also better informed and more competent than most fitness trainers. The good ones will also walk you through a basic physiology course so you can understand the why of it all (why did I become injured, why does this prevent or reduce the risk of a future injury).
This is a big part of why I have avoided it thus far... I have a hard enough time getting a doctor that I feel like cares about my issues (rather than just getting me out the door as quick as possible) enough to listen and understand. I don't want to spend a bunch of time and money trialing different therapists. I wish there was a resource for this online.
I agree though, if I plan to continue the type of cycling I did last year, it's probably going to become a necessity.
It is super possible to have imbalances even with regular training. Muscles that are weak will not be engaged during compound lifts unless specifically made to engage, either through isolation exercises, or through awareness. A personal trainer or physical therapist can help with either path.
I did some things on-and-off for posture (mostly rear delts), but what I did consistently, and think helped the most, was heavy (for me) deadlifts.
I'm curious: how many pullups can you do? I ask because they take a lot of lat strength, and your lats do a lot of work holding up your back.
I didn't use a coach, but did study a lot of videos on deadlift form and also videoed myself to check I was doing it properly.
I've heard deadlifts are one of the best exercises, I can't wait to get back to PT and get a personal trainer so I can do those correctly. I doubt I've done enough with lats.
You're right, though, that deadlifts (performed correctly and safely!) are pretty amazing for your back in general.
If you've got something up high to tie a band to, that's something.
(Disclaimer I'm not an expert). I think a common bad posture in-front of the computer is the one that rotates your shoulders forward which overloads some muscles in the chest, which are antagonist of the middle traps, middle traps get weak, and your back falls forwards, face pull is great exercise to make them stronger. Another common one for those sitting long hours, is the tightness of the psoas, which can cause hip problems, and knee problems if you try to run without stretching, I think the antagonist is the buttocks, that gets weak from sitting and you would need to exercise to correct the hip problems.
Don't trust my comments, I just wanted to put two examples of mechanism that I learned, but I don't have enough knowledge to explain it properly or be 100% sure this is correct, always consult with a pro.
[1] https://www.physio-pedia.com/File:Trapezius_animation.gif
Inversion is the key to decompressing the spine/hips/neck and you only need to do it a few times a week for ~10min each time. I go to a local park and hang upside down from a sturdy pull-up bar for 2-4min three times.
You could also do it at home with a pull-up bar, or get even fancier and buy an inversion table for ~$200.
I know I'm sounding like an infomercial here, but it really works.
For me, physical therapy did nothing, and I suspect my issue was fundamental in that my musculoskeletal system was underdeveloped and working out was the only way to fix it.
Like a lot of people working in tech, I've had persistent neck and posture issues for years. I'd love to see you expand to cover those, focusing on the many smaller muscles in the neck like SCM/Scalenes/Occipitals/etc.
Another great area to expand is 'click where you have pain' and it would recommend certain stretches, weights, trigger points, etc. There are common pain referral patterns that most people do not know about and I imagine that would be very helpful for people who don't have easy access to physical therapy or even feel they are candidates for it.
After casually mentioning my neck issues to people over the years, I've found so many people open up about persistent pain they have but that they're not addressing because it hasn't reached a bad enough point. I think that's an ideal audience to target with online resources like musclewiki.