Yeah, given their level of success without marketing expenditure (ie, its likely to be a good product) you have to wonder if they would have been able to multiply that success with some marketing effort.

On the other hand, putting (apparently) 100% of their effort into product is maybe the reason it worked.

I personally think a great product is table stakes for success, but I’m repeatedly shown to be wrong ¯\_(ツ)_/¯