To be fair - it SUPER does. Being down frequently makes your competition look better.
Of course, once you have the momentum it doesn't matter nearly as much, at least for a while. If it happens too much though, people will start looking for alternatives.
The key to remember is Momentum is hard to redirect, but with enough force (reasons), it will.
Few companies (and none of the companies I worked for) are “momentum”-based. The typical company grows because incoming cash flow allows to hire more salespeople and develop new features attracting new kinds of customers.
If people tolerate 10 monthly github failures, they can most likely tolerate one hypothetical hour of downtime from one physical server failure for some random Saas product you're selling to them.
Of course, once you have the momentum it doesn't matter nearly as much, at least for a while. If it happens too much though, people will start looking for alternatives.
The key to remember is Momentum is hard to redirect, but with enough force (reasons), it will.