I think it's just that Discovery didn't want to let it end. After Adam and Jamie left, they had like 2 more seasons with new hosts. I actually don't know if the quality of the show dropped, I never really gave it a chance.

I thought the same thing till I remembered they booted Kari, tory, and grant for having the gall to ask for fair pay. Iirc they tried to make finding a new crew a whole "thing" on the show and the fans absolutely hated it. Adam likes to spin it as "production costs going up" which yeah, having 3 Unpaid inters asking for fair compensation is a cost you should've budgeted for after 7 or 8 years. Couple that with Adam's reputation for being a drama queen and an absolute nightmare to work with, and they show was pretty cooked by the end.