How do you know there's less DIY at individual tables? What's your source for that information? There might be more demand for official product, but maybe that's because there's much less of it than there were with other editions of D&D. Just think of the glut of products they had for 2nd edition. Were we ever a DIY hobby?
I KNOW we were once a DIY hobby because ... there was a time when you were unable to play D&D without table modifications. The first 16 years of the hobby had the primary game that was unplayable by RAW.
Moreover, the vast majority of early TTRPGs were just people's houserules of D&D that were modified. They did ... it ... themselves. And then published the results.
I feel like ... there have been threads about this? Maybe .... a book or two?
That's kinda "res ipsa."
But sure- I have not gone to every single person's table today and verified my observation. Also, please use the spoiler block for REALLY LONG POSTS. Thanks!