Everyone wears headphones at my place if they're trying to focus. Last job literally handed out construction ear muffs.
Also, all the rooms are taken up by meetings. Mostly by business/product. There's no rooms left for engineers to hash things out, frequently.
I cannot adequately describe the horror this sentence induces in me.
I haven't really been in a startup office that wasn't this way in quite a while. First startup I was at played music all the time - that wasn't great. Second place (not a startup) had engineers stationed next to sales people who had to be on the phone all the time at their desks. Third one - the sales folks were further away but everyone not in engineering was so loud that they gave those muffs out (lots of customer service reps sat near engineering too - lots of phone calls). And now I am at one where everyone is next to everyone even at a billion dollar company. Each person gets a 60"x30" desk (it might be smaller actually) and they shove 6-8 of them together in groups of 2x3 or 2x4. Then put them in really close proximity where you have about 12-18" between your chair at your desk and the person behind you. Not uncommon to run into the person behind you. This is for a company with over $100mil in funding. There's about 100 people in the office. It's not a very large office at all.
Most people just don't join the company if it's an issue - but I don't think anyone has cited that as an issue yet. Most people complain more about the terrible codebase or poor management or bad numbers or poor compensation. (Inclusive or)
This doesn't work for a lot of people, including myself. Being sonically cut off from the environment causes many people a great deal of anxiety and stress.
White noise generators and proper office design mitigate nearly all of your concerns. There is obviously etiquette to having quick conversations around colleagues and meeting rooms are always available for deeper collaboration. For the most part our work is planned out carefully, most problems can be resolved via a couple of quick Slack messages.
I feel socialized and look forward to coming to work. If I worked in a small 2-3 person silo I'd feel like an instrument of industry rather than a family member. I know that sounds trite but it's true, feeling part of a larger team / the business as a whole is incredibly motivating.
I admit my concept of small private offices is marred by my own experiences of those work environments which have all been just soulless bad places to work. I know that is not the rule for cube/small office workplace design.
Long conversations do deserve private space, but this can be resolved by having ample meeting spaces.
So now you have to coordinate on Slack to go to one of the shared team meeting rooms instead. At that point you might as well have your conversation in Slack, even if the person is sitting right next to you. And that's the state of open offices today, co-located but void of any actual collaboration.
I've worked in single person offices, 2-3 person offices and open offices. 2-3 person offices where everyone works on the same thing is the best, by far. Remote work is the new private office, not quite as good as a 2-3 person office, but infinitely better than an open office.