It's also easier to run a feedback loop. If you implement Y, but Amy doesn't give you $5 a month, what are you going to do? Knock on her door? Users have no idea what they want half the time, anyway.
If you build a product and no one cares, it bruises the ego a bit more, sure, but if you self reflect, you can eek out your own bad assumptions, or bad implementation, or maybe a way to pivot that keeps your product ethos.
Which is where the bulk of the other 80% of features come from. It’s a cycle.
You start as you describe, you expand, you end up with this enterprise monstrosity, everyone using a different 20%. New tool comes along, you start as you describe…
Hopefully you can afford to say "No" a lot.
Are your customers selecting one of five features in your product, or choosing any twenty from among a hundred?
Especially when, who the heck has time for trying out a dozen products? That's at least a full day of work, which probably costs more than the software itself.
No, you just read a few reviews to find the best full price option and best budget option and figure out if the budget does what you need or not. And often go for full price just because you don't even know what features you'll need in 6 months which you don't need now, so safer to just learn the option that is the most future-proof.