GNU already included the best C compiler, the best text editor, and a number of other development tools, before the Linux kernel came around. For the people who were on the internet already at the time, it was quite notable.
It is certainly true, though, that without Linux, GNU might easily have collapsed in the early 1990s.
It might depend on what you were doing. I mean, Cygnus was founded in 1989, and I think they had revenue by 1990. So at least some people considered it so viable they were willing to pay a tiny startup hundreds of thousands of dollars for it by then.