My personal theory is that this is a side effect of startup/SV culture trying to make work seem like an extension of college. The office is a “campus”, where you get fed, socialize, and sometimes sleep/crash on a couch or the floor. College students go from freshmen to seniors in four years. So now the work titles also do the same.
It's just a title. Means about as much as VP in banks.
Also, only the 2nd or 3rd step on the ladder. Most places with 3-5 YOE seniors have Staffs & Principles above them.
Which have also been watered down in order to give the seniors somewhere to move up to. So the rungs get relabeled, but the ladder doesn’t actually reach any higher.
And just as empty and ultimately demoralizing. It feels great to “advance” so quickly at the start, but then most people are stuck at some level of “senior” for the next N decades. Why not have meaningful titles commensurate with actual levels of mastery?
You’d have to keep people around longer. Thing is - people don’t want to stay in the industry as software ICs. They want to be in product, management, or something else. Being a software engineer is often just a stepping stone to the next thing.
My two cents here is that senior doesn’t mean the same thing at every company. But title inflation is a good way to snag great hires away from other places and retain employees