Robinhood isn't a bitcoin company. That's just a feature they have. Its main product offering is the commision free trading--and their presence pushed a lot of big players to adopt the same offering. The wallstreetbets gang is silly and all, but I think they have really democratized stock trading, and made the whole idea seem much more accesible. I think they founders are former finance guys. I hope this doesn't sound like guerilla marketing. I don't even use the app, I have used it but I'm just not that interested in picking stocks. I just think it's cool as an ex-code monkey to entreprenur story.
With mutual fund companies, including Vanguard, generally you can open an account directly with them and buy directly from them (including partial shares, automatic monthly purchases, and dividend/capital gain reinvestments).
How much did it cost to place a trade for a $100 stock previously? RH definitely helped more people gain access to directly trading shares on the stock market, regardless of whether or not they were responsible in doing so.