This has not been my experience. Game developers I've worked with have generally been pragmatic and willing to use the best tool for the job.

Also triple AAA isn't that old! There's not a generation retiring quite yet :) People who want to still be in the industry are. I've seen the industry get older on average as I've worked in it.

Forms of middleware have been there since the early days of AAA style games - sound, video encoding etc. such as RAD Game Tools