>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.
This wasn't true in the pre-2000. It was only the DotCom(tm) era that spoiled VC's who all wanted hits within 36 months.
The history of the valley was the history of slow investments. Semiconductors are money hungry and slow--yet VC's invested in them until about 2000.
I would argue a lot of the lack of progress in tech is because all the VC money is chasing fast returns.
I find Musk insufferable, but, credit where it is due, he put investment money into two VERY slow industries.