Possibly the best thing about the streaming age is that sci-fi shows don't have to rely on Fox to stay alive.
Sci-fi shows on every network have always struggled to stay alive. I grew up in the '70s and '80s, long before FOX existed, and it was frustrating being an SF fan back then, because it was unusual for any SF/fantasy show to make it more than one season, or even to reach a full season rather than being cancelled halfway through. That was no different on FOX than on any other network before or since. Genre shows have always had a hard time surviving on commercial TV because they cost more to make than mainstream shows and had a smaller audience, making it doubly hard for them to turn a profit.
The difference is only that FOX bought so many more SF/F shows than any network before it, or any broadcast network since other than UPN/The WB/The CW (percentage-wise, since FOX has been around longer). Multiply that higher number of genre shows times the typical percentage of cancellations, and you get a high number of cancellations. True, FOX has bungled their handling of individual shows from time to time, as with Firefly, but overall they've been one of the networks most supportive of genre shows, continuing to buy them in large numbers while other networks largely avoided them. (The network that really hates sci-fi is CBS. Genre shows have been rare on that network for the past quarter-century or more. At least FOX kept trying.)
I think another part of it is that FOX has had more genre shows that audiences really connected with, so that their cancellations were especially painful. I've seen lots of genre shows on ABC, NBC, etc. come and go with little investment from fandom, so their departures had little impact.