"hey guys! lets take a model that has been proven effective by many years of fierce market competition, and disrupt it by doing for free!"
I think this model is so tempting because it has become easy to persuade investors of value with user numbers (by itself a truly meaningless metric).
People are better at gaming a system than building useful new products. If the institutions say, give me a large user base and we will give you money, the next day you will have a line a mile long with startups with HUGE user bases, because that is what they were told to do to be successful. Easiest way to do that, as you say, giving away for free what used to cost money.
Between destroying the natural world and being total sociopaths hell bent on obtaining money/power at all costs, this species is fucking sick.