Doing even 10 on-site interviews is incredibly draining, especially if you're actually contributing at your full time job.
I interviewed around 2 years ago at about 10 places as well. 10 days of interviewing for 6-7 hours was so mentally exhausting that I just took a week of vacation after all the interviews were done.
I had my 10 interviews in a span of 3 consecutive weeks.
It's definitely not worth an engineer's time to resolve random customer issues, especially as Stripe has grown from ~500 people to ~7000 people.
Gone are the days where all the engineers were intimately familiar with every product and could offer you their tribal knowledge to resolve your silly issue.
Stripe is now a big corp. and there is no incentive for engineers to waste time on HN resolving customer feedback. There are proper channels that are better equipped to do so, namely the "clueless customer support agents" you speak of.
If your issue is truly some bug in the backend and not user error (which it usually is) it may eventually get surfaced to engineering.
e.g. a university student (2025 grad) who is working part time is in this list.