I had guys with thousands of jet/airline hours, one guy with 747 time, a c130 bro, and other experienced people in my class at Mesa. When you join the airlines you are nothing more than a seniority number. You start at the bottom and get paid accordingly. Experience/skill means nothing other than getting that seniority number. Upgrades to captain aren't based on anything other than seniority number, and maybe some captain recs.

That is the whole reason the airlines are the way they are. Any other profession, you can take your experience/previous pay with you. Not here. Which is how the airlines can screw pilots, because after a few years, your seniority is gold compared to starting at the bottom elsewhere for something slightly better.

Also, mainline can whipsaw pilot groups against each other in the regionals for this reason, or force a sham bankruptcy/closure to make one regional go away and transfer planes/pilots to other regionals, resetting their seniority/longevity. They just became $20k/year FOs instead of $100k/year captains. Labor costs reduced by millions overnight. Comair is a good example of that. Plenty of others as well.

There's more to it than that (unions, railway labor act, etc.), but there was a lot I didn't know coming from the mil to airlines about how it works. But that's the long answer of what your experience is worth to airline management. You are no better than a kid with restricted ATP mins of 1000 hours who flew a pattern in a 172 instructing the whole time. The only difference is your stay at the regionals will be quick, less than a year probably, and you won't get to enjoy food stamp wages for very long.