The official user guide for Skyrim explicitly states that alt-tabbing can cause crashing. Maybe you're using some form of wiccan magic to avoid this issue, but Bethesda themselves acknowledge it's an issue. Perhaps you're referring to Skyrim Special Edition?
Can being the operative word there. This is just dishonest. I've got about 200 hours in Skyrim (back in what 2011 or 2012) sometimes you've gotta double-alt tab back out sometimes so the game looks like it has crashed. Loads of games work with that trick btw (e.g Rome Total War, Medieval 2).
But it is rarely an issue with new-ish games (in Windows). But is a big issue in Linux with proton with a lot of games I've tried. Rome Total War 2 (which was at the time infamous for it bugs) could be minimised and left running for hours without issue and that is quite an old game now.
Always hit esc before alt-tabbimg out, otherwise I always get two cursors with differing sensitivity. And only one is actually the cursor. It doesn't crash until you re-enter and I can usually fix that by selecting it from the task bar, and when I get a blank screen I then alt-tab through all the open applications and back to skyrim. Wiccan magic indeed.