> Sounds good in theory, but what if your company decides to reduce investments in the spreadsheet product and instead transfer the product team into a much faster growing product segment, e.g. SAP integrations?

> Then the perfectly qualified PMs start from square one again.

Exactly the same point holds for programmers: what if (say, by becoming acquired) a company has to switch from being a, say, a Deno/Vue.js shop to becoming a Java shop? Exactly.

So the answer is: don't do such radical changes in the product portfolio and way of doing work if you don't want the employees to more or less to start from square one again.