Consider how much less influence people would have without it. Microsoft has been forced to backtrack on customer exploitative shit multiple times due to the very real threat that it would lead to linux getting a huge boost.
Without a functional Linux Desktops for users, there is no doubt to my mind the windows app store wouldn't be the only way to install apps on windows and there would be no way to sell an app that installed on windows without paying microsoft the standard 30% of total sales. The recent fight between steam and microsoft illustrates this perfectly. But they have tried every few years, claiming anti virus, child protection, anti piracy, convenience, anti spyware, anti ransomware, and well its always been the pro microsoft profit in reality ... But they lost each time, because each time too many of its users just threatened to move to linux. This is essentially the only reason you can install, run, and develop apps on windows without everystep including microsoft fees and licenses today.
Look at how stagnant and shitty matlab used to be, and its exorbitant priced to understand what happens when FOSS fails to provide. The niche matlab used is the, at the time, almost non-existent overlap between FOSS programmers good at both GUI UX, tutorial writing, and math. This changed with the FOSS python, numpy, scipy, matplotlib, and pytorch projects.
Matlab has gotten extremely much better in the last few years, and its mostly because they finally got competition, they have also started to rapidly drop their effective prices for new users, but its too little too late, and it will never return to the stagnant cashcow it used to be. Matlab was is a troll sitting on a shitty toll bridge while both trying to destroy similar bridges and maintaining its own toll bridge as little as possible. In the last decade FOSS mortally wounded it in passing.
Inversely reduced FOSS influence predicts exploitation. as shown by how astonishingly bad the walled gardens of consoles and phones are. They have gotten away with being astonishingly shit, mostly because FOSS was intentionally and successfully made too hard to use on them.
But these are just visible examples. The great effect of FOSS has never been what it brings about, it is in what it prevents from occurring in the first place, and that, by definition, will never be easily visible.