Your average mid to senior SWE is too far from the actual use of the product to actually do that well though.

There are some smaller businesses and selectively structured ones where that's not the case but for the most part organizations keep engineers from interacting with the customers enough to really know what the customers need and want.

There are some cases where a savvy engineer can say "well if I unify X then it'll be trivial to make Y self service and that'll make redundant an entire category of support tickets" or "we've been getting a lot of requests for X, maybe Y should be extensible so that those can be trivially accommodated" but by and large engineering teams are not positioned to have the knowledge to identify these things. And this is mostly an intentional organizational architecture decision.