That’s not an issue with FOSS vs proprietary, but with large corporations needing to be broken up.
FOSS isn’t immune to that, its a known thing that large corporations can use their dominance of a market segment to infiltrate even totally open standards and make demands with the threat of leaving the standard (and therefore resigning it to becoming irrelevant).
This is especially true of web standards. Chromium is FOSS, yet Google can use its absolute dominance in the market place to force through changes to things like HTTP standards (also FOSS). My understanding is Microsoft and Google both have strong-armed stuff into C++ in the past as well