Industry makes a living on technology progress. If someone makes a living on pushing lock-in (MS), they are doing a disservice to the whole industry. It has nothing to do with FOSS - it's about progress in general (lock-in is the opposite of it).
You didn't disprove what I said above. Duplication of work costs more money, and no one likes to waste money, especially when reasons for that duplication aren't even technical, but are caused by crooked vendors who force that extra expense on others with lock-in.
> Professional game developers don't care
They care about their budgets. Your idea that duplication of work is welcomed is complete nonsense.