But if that were true then the PMA and similar industries should be flat or declining. Except they’re not. Some of those industries are actually "booming." However, the qualifier as with any product is the market in which they serve and the private Part 91 market is not one of those.there is incentive for competitors to undercut the incumbents -- until regulatory restrictions stop them.
Regulatory requirements have always been a cost of doing business vs a restriction. Have been procuring parts for a very long time from many different sources and do not recall any vendor ever implying they cancelled or didn’t pursue a product due to regulatory issues. No profitable market, all the time.
There were even times when some vendors would retool for a discontinued part provided we ordered a minimum to meet their profit minimums. So I don’t know where people consistently get it’s a regulatory hinderance. That is not my or others experiences at all.
Even at the aircraft certification levels, OEMs are still certifying new aircraft for viable markets. Both Cessna and Beech have provided 2 clean, sheet aircraft in the past 5 years. No regulatory restriction holding them back to include GE with their clean sheet engine design for one of them. But you won’t see one for the ever-declining Part 91 recreational market. Simple economics.