But very rarely does it have properly synced well-written subtitles, multiple audio tracks, and a quality encoding. Find a combination of those that works together without 30 minutes of fiddling with the subtitles and you've probably just wasted your weekend even if you frequent high quality private trackers.
It's also generally harder (not impossible, mind--same as the above) to find extras like cast/crew commentary, blooper reels, etc. These wouldn't be hard for studios to provide in some theoretical Movie-Steam.
Even in the case of games that don't use an internet connection to verify themselves, though, Steam is still more convenient--automatic patching without needing to try and find a new crack every time, no need to hunt down files or patches every time you want to reinstall, less concerns about malware, etc. If Steam had a monthly fee, I'd probably still see it as worth it up to a certain point--definitely not the 100$ you mention, but considering how much use I get out of it it isn't completely off the table.