If their paying customers want something, then that's perhaps a different story, and is governed by whatever agreement (tacit or otherwise) is in place for the purchase.
But if you aren't paying, you aren't owed anything. Not a single thing.
I wished those people could be transferred back to the pre-FOSS days when your disassembler was one of the more critical tools in the toolbox if you wished to fix vendor bugs. I distinctly recall reverse engineering the ROM of a laser printer board to repair a bug that the manufacturer just couldn't be bothered to deal with (Tall-Tree systems Jlaser, I'll never forget). That would have been a lot easier if it had come with source code. These days for me it's either open source or you can keep it.
I wonder if this shift can be attributed to influencer / social media culture. That is, these things exist to get "likes" and "engagement" and build "communities" and "brands" and whatnot. So your average person, someone who even knows a bit about open source, might think that any maintainer worth anything would want those things as well, and see it as not just worth it, but required to provide all the extra free labor required to get those likes and promote their brand.