Not sure it changes EVERYTHING as the issue of sales and marketing still favours LinkedIn. Sales/Marketing is very expensive and sometimes even difficult to predict. Building is not everything.

Right, the point Im trying to make is that if someone has a requirement, they can build it on their own, for themselves, at much lower cost (because they don't need sales and marketing for themselves).

It was always possible (hire software devs to do it), but the bar and cost is much, MUCH lower.

Sure, no doubt about it.