At some point they got so popular that I just felt like they sold out. I felt like I was just watching 1 giant ad with all of their videos trying to get me to buy something.
Also, some of their rants that they started going on got annoying. Seemed like at some point they lost the chemistry that they had together. I just enjoyed watching their banter and them doing goofy stuff.
Huge agree about pushing their merch! They're shameless. I used to watch every day for years but stopped a long time ago; when every episode became a food episode. Their podcast (Ear Biscuits) is a bit better, it's more them talking about things long form, just being 40+ year old fairly normal (if not very successful) guys. They've talked about quitting GMM, I think once their various kids are done with school they'll pack it up (the main show at least). They both have other passions but it's really difficult to stop when you've built a successful, working media company with your childhood best friend, even if they're both ready to retire.
They actually bought Smosh and brought Ian and Anthony back, and then sold Smosh back to them a few years later. That was a really cool move to me and and got them a HUGE pass in my book, they're stand-up guys.
Full disclosure: despite not watching much of their video content anymore I still went and saw them on their most recent tour (about a month ago, it was a gift) and had a great time. They did some of their games but modified them to be specific to my state, did a food ranking with some local-foods, and of course had a couple musical numbers.