trocadero parent
I think what has changed is the shocking amount of money that recent start ups are burning. Snap burns more in a year (~$1 billion) than Facebook did in it's entire life. Uber has burned ~$10 billion during its existence. It's hard for me to picture a company raising that amount of money on the stock market.
Tesla has lost several billion dollars since its IPO in 2010, and that hasn't seemed to have slowed the stock down at all.
Tesla only raised $270 million in their IPO. They've subsequently raised more, but their initial a pretty far cry from the billions Snap/Uber needed.
Tesla has raised billions of capital from the public markets
It's not that hard to picture Snap raising billions in the stock market: the company got $2.7bn at the $3.6bn IPO last year. Twitter raised $1.8bn in 2013. Their problem is not lack of financing.