That happens even without snow. I've been stuck on Amtrak trains because there was some object on the track (crashed vehicles) and the train just sat there for hours and they refuse to open the doors even though were were in the center of Oakland and could have happily just walked out.
Amtrak is not a great example of how trains should work.
Amtrak is particularly vulnerable in that they lease their tracks from freight companies, who generally prioritize their own (much longer) trains over Amtrak. So a small delay can snowball into a large one very quickly.
Amtrak is not a great example of how trains should work.