I find that to be an annoying thing with Japanese software in general, gaming or otherwise: more proprietary garbage than Western software and practically hard-coding it to 100% force you to use the software in the way THEY intend for you to use it, not how YOU want. Makes for worse Linux compatibility at best, if any at all, compared to Western software. Note that I'm purely talking about native or straight Wine Linux compatibility, not Steam/Proton, which works around those issues well.
In an ideal world everything would work out, but for some business it is a pretty huge commitment for what was less than 2% of the market just a few months ago. We certainly lost money porting our game in Linux at that last place I worked. It was before Proton though. Obviously each case is different, and some games work on Linux out-the-box due to Photon so this become a non-issue.
Not sure I want to name the game because this would make me very easy to identify from my post history. It's a game on Steam that sold over 250k copies. My boss promised a Linux version very early on because they thought it would be easy, but we ended up being stuck with that promise.
From my own experience, "not bothering" is definitely the better business practice since chances are you won't make back the development costs.
Maybe Steam Deck and that porting library have improved things but a decade ago it would have been better business to just give Linux users $20 to not play your game.
I believe the PS5 is partially based off of FreeBSD and I don't think there is as strong of a gaming scene on BSD (even relative to the size of its userbase). I feel like there would be some rather large leaps going from a tailored console OS to a more widely available alternative OS.
Looking at Destiny. Game worked okay on Linux before they integrated Battleye, which HAS Linux support, but Bungie just doesn't want to interact with it.
This is why it's mainly larger developers that care about their community that implement Linux support. Take valve for example. Wonderful company that cares about their playerbase more than the average game development team. They have Linux support on almost all of their games as far as I am aware. Bungie is a decent company but most of their community doesn't want to play on Linux anyway, so they won't bother with it. However most teams that are smaller or care more about money than players won't do it.
Valve is definitely an exception. I am not sure why, but it is pretty much in the open that Gabe Newell has a bone to pick with Microsoft and he has been throwing money at Linux for over a decade to break their monopoly on gaming. I'd argue that this has nothing to do with their love for the community and more so with Gabe's personal vendetta against Microsoft.
Reality is that most game devs, most executives and most people in marketing don't really care about Linux. It is good PR to support Mac and Linux, and some of the geekier developers will go the extra mile to support it, but I think it is common in the industry to assume that Linux users are not gamer, or that they have enough knowledge to install a dual boot. They don't care in the sense that they don't even think about it, its not even on the radar for most game companies. Most studios probably never even had a discussion about it. That is how irrelevant Linux has been to gaming. Hence why Proton is such a tour de force.