Yes, this seems likely correct to me as well. Small wonder that I agree with a successful startup founder. 
Then again isn’t the fact that Fibery does not do one thing exceptionally well actually both a positioning and product problem? 
Interesting. I’m not sure the rest of your post necessarily supports this though. Your approach is basically to try to do most things that “product companies” (where is this vague term actually defined? ) need to do, and do most of them “well enough” that the collective result is “exceptional” in its own way, right? That seems like an extremely difficult and vague problem to solve in a way that is compelling enough in an obvious way to companies using existing solutions such that they switch.
My perspective is that a narrower focus or “wedge” may be a better or even necessary way to approach this. “Product companies” is not really a good wedge IMO. Oh dear, I am starting to depart from agreeing with successful product founder and I feel (genuine!) trepidation that I might look a fool. But so be it. 
How do you evaluate when this has happened? How do you get there without better growth? How long can a company go with MRR < Burn Rate?
Yes, exactly. It made it really easy (and aesthetic+fun) to do something that many companies need.
They do this already quite a bit. They have a whole category on their website for it. 
Thing about such cases/stories is they focus on the “won” cases, not the lost cases, which are almost certainly far more important. It’s IMO less important to know why someone chose you than why someone did not.
Don’t they already have this with Templates though? Maybe needs a bit more work, but basically there. And they are even part of new workspace creation/onboarding. It ties in to a further idea/suggestion I have about onboarding though:
This should basically just be part of the onboarding flow alongside template selection (the prompt about what kind of business/user you are), e.g. “Do you have existing data to import? Try one of our awesome integrations (clickable list) or import your CSV here → [button]”.
I do agree with this and I actually think it’s already a Fibery superpower that is not talked about or demonstrated enough. Few other tools have integrations with anywhere near the comprehensiveness and power of Fibery which can essentially replicate the data model of many other apps.
Anyway, it is hard not to be an armchair product manager. It’s kind of fun. But really there are no easy answers. As soon as you start to dig in to any obvious product niche or potential wedge, you generally find lots of products dedicated to that thing, and some doing it probably quite well, while the many others in the space fail to gain much traction, and Fibery might well just end up as one of the “also-rans” there too… But maybe, just maybe there is some clever wedge not yet realized…