The reasons companies (listed and otherwise) give stock rather than cash are: 1)cashflow - it allows them to compensate people without affecting the cash position of the business 2)tax - sometimes it's more tax-efficient for the company than cash compensation 3)incentivises retention - vesting keeps people on the treadmill, especially if you re-up people while they vest so they would always leave a lot on the table if they walk. This is standard practise at Wall St firms so it's not SV-specific. 4)incentivises long-term value creation - if people get granted at around the fair value of the company when they join, then when they (exercise and) sell, they receive a share in the value they helped to create. It very much more direct than other forms of compensation 5)flexible - it's very difficult in many cases to adjust people's cash comp downwards. On the other hand if you structure a big piece of their annual comp as a discretionary equity bonus you can flex that 6)clawback - unvested equity is easy to claw back in the case of employee malfeasance. Cash is pretty much impossible to get back short of a lawsuit and even then, good luck.

I totally get that people's long-term financial well-being is often too correlated to their employer's stock price, but it's really no mystery why firms do this. It's not at all an SV invention either, it's very similar to the template used for a long time by Wall St firms.