>Maybe it's just that companies went public at a much earlier stage back then.
This. My father worked for a few semiconductor startups in the 80's, e.g. Xicor. Liquidity events were trivial compared to now. Small company's with competency and focus could exit with a proprietary tech play which satisfied everyone all around (founders, vested employees, investors, industry). Rinse and repeat for two-three decades and we get the foundations for Information "Tech" startup culture.
Maybe it's just that companies went public at a much earlier stage back then.