anidais: Yeah, GOG support staff must be small.
Guter: So, why then not transfer this process to the publishers/developers, like on steam?! By adjusting their platform for these steps.
If they are unable to do this, and unable to do the necessary things themselves because of lacking resources, they may be doomed.
When other stores that actually were selling oldish games (Mind you, I'm writing about late 2000s up until 2010, mostly). they actually sold you files that may not even work. There was no configuration or other work to ensure they would work on modern systems. At the time, GOG was the only store that actually put the effort and ensured they would actually work, but, of course, this required lots of research and effort on their part. Updates were not a problem though, since it's not like those games were getting any anyway
Fast forward to nowadays and things have changed somewhat, other stores have started putting in way more effort into ensuring actual compatibility (Although I would still argue GOG puts still the most effort individually per product, barring attempts at funding/developing the WINE framework and bringing its own hardware), and GOG itself is now selling way more recent products that often still get updates. It also retains those stricter guarantees that made the most sense when it mostly sold oldish games (Since, for those, it's not like you could ask support from developers of studios long gone), but are now extended to all products regardless if they're undergoing active development or not (Products still being development make the most sense shifting responsabilities to developers instead of publishers/platforms).
It seems (As viewed from the outside) thus that GOG utilizes an unified publishing pipeline with a waterfall-like method of operations for all products regardless of their development status, and, as such, products still in active development get delayed because other work on other products may get priority due to timing constraints. Let's also not forget that GOG also provides things like offline installers (Which are probably too specific of a practice to shift onto developers), and performs a bunch of internal tests (That, again, cannot be shifted onto developers without trusting them completely). Add to this staffing shortages and you get the result you would expect.
It's not the case of all products, though. I personally own Tunguska: The Visitation (Still being updated, made by an indie developer that is literally a single person), and updates there come often and basically at the same time as other platforms. Maybe because he's a single developer, there were ways to offload things a bit. On the other hand, when DUSK developer was asking for his game to be published on GOG, it took a very long time for it to be accepted, he himself mentioned not receiving any answers.
I think it's merely an understaffing problem, with timing concerns dictating if/when deelays happen. It's not strictly a budget problem, though, since it's apparently said that GOG is being run on a very strict balanced budget allowance as a deliberate decision by its owners, and they must always report good enough returns. Probably they want to ensure not going public to attract more capital, but if they were to do that I wouldn't doubt they'd be able to attract some degree of decent offers. Let's not forget that the government of Poland has sometimes given incentives to studios, so they may also want to retain the company at 100% Polish-ownership to ensure those incentives flow.
Of course, adopting a different pipeline based on if a given product is undergoing active development or not may also be a solution, but it may not work with some of GOG's licensing guarantees being offered to users.