Yes. Nobody I know will play in the London philharmonic. But we figured out enough to play a cover band in highschool, and I'm figuring out enough to learn passable music production. On that note, from what I've learned from their interviews, many of the biggest producers have never taken a music lesson.
This isn't me arguing against lessons writ large, simply pushing back on the notion that they, and other barriers to entry, are not barriers at all. There are other paths.
But if your goal is to perform; sure, you'll be able to play simple compositions, but anything complex will pose a challenge without a teacher (or even good material that makes you aware of what to look out for). I think that's what your critics are trying to point out.
The real problem here is you're equating learning music theory with 'learning the piano'.
The variation in results is much higher if you go off the well beaten path.
Secondly, if you think learning piano is comparable to programming or art then you are completely mistaken.
Edit- added here since HN doesn’t let you comment anymore if you get downvoted too much.
With programming, the feedback is immediate and accurate. You know if your code does compile. You know if your logic is bugged or if your algorithm is too inefficient. If the code you write doesn’t work, somebody can give you their code to bring you up to speed. This allows you to immediately address your issues.
With piano, (at least in the beginning) you are not qualified to judge if your hand position is right, if your posture won’t give your RSI in the long run, if you are even playing the right notes, if your rhythm is off, if you are reading the sheet music wrong, if your pedal is timing subtly off or if your legato is correct. You can practice for hours on playing the wrong thing. A teacher can help you get this stuff to get fixed. Secondly, unless you started ear training as a child you won’t ever be able to develop absolute pitch. Your ability to discern pitch and listen to the very music you are playing is already at a disadvantage. You’re basically blind and deaf and you have no idea what progress should look like apart from superficial judgments.
Music, in and of itself, is pretty simple and natural to create: clap your hands, stomp your feet, sing a little. There's a low "skill floor" on it.
Programming has a much bigger skill floor - syntax, memory management, indirection, and other conceptual forms of knowledge. But once you have the concept, it doesn't matter a great deal what exact things you type if it's implementing that concept successfully.
But music has tradition, and not just one - it's one per instrument, with subsets for different playing styles. When you get classical training(which I did) there's a lot of pedigree built-in to being a "student of so-and-so". You learn technical competence - how to not injure yourself by playing(RSI is a big one but it also occurs with posture, breath control and so forth) - but also to express the music interpretively, a translator who turns notes on the page into a dynamic performance, and this involves both repetition and attention to detail that is suited for coaching. Music can be very athletic at the world-class level!
Over time I've been able to cross over the two worlds - finding ways of programming that are a little more iterative, more like performance - and approaching music from a more theory-and-concepts perspective has helped me understand compositions beyond the surface expression. But the broad differences still remain.
And take everything that has been written (barrier to entry, etc) and add COVID isolation into the mix. We are still in this mess for another 9 months about.
Im not arguing about teacher vs app in the most generic sense...but one can spend 30 mins a day with an app on wireless earphones and get to a pretty decent State for playing is worth it.