Is having a network mandatory in launching a successful startup in 2020?

I've been watching people like @steveschoger and @levelsio launching their products to their followers with great success. The product in itself is nothing special (a job board) and it's clear that if someone without a large reach built a similar product it would flop.

There is no shortage of people on imdie hackers making decent products but falling short on the getting their product out there.

So if the primary problem people are facing is marketing their product and a network makes it considerably easier to promote your business...

Is building a network the most important factor in your business's success?