Stock price doesn't have any effect on the value of ESPP at Microsoft, but you're right that it does on the RSUs. At least one company exec has directly proposed this as a counterbalance to "no pay raises" (From 2023: https://www.businessinsider.com/microsoft-exec-defends-compa...).
That said, anyone can own Microsoft stock. With respect to current employees - the common wisdom has always been not to own too much stock in your employer, with the rationale that if things aren't going well and the stock is tanking, you're likely to get laid off and then you're even worse off. But these days I'm thinking that the opposite is true, at least in bigtech: The more likely scenario is that you get laid off regardless and the stock goes up in response.
ESPP is discounted from quarter end price (I vaguely recall it being either last q or following q, whichever is lower but that seems like too good to be true). So constantly increasing share price does have an effect, both short term and long.