I have a unique perspective in that I have been going to Magic Mountain since before Six Flags bought it. The early days were fun - less crowded than Disney, though admittedly the rides were not as good - but - I would have picked it over DL every time. Fast forward, decades later, yes, I like the new rides and the massive number of roller coasters, but the crowd you will see at SFMM CAN BE (not always, but the norm), shall I say, not very courteous? Maintenance can also be an issue with ride capacity dictated by breakdowns rather than scheduled maintenance. DL is the opposite of that with crowds 90% of the time are very courteous and maintenance is first rate. It makes me sad that SFMM has changed so much over the years and I do miss the way things used to be. Knotts in may respects falls in the same category.
So yeah, I think everyone else's comparisons to dining are spot-on, but I'd also compare it to shopping at
Walmart - if there was nobody there, I could look past the glaring florescent lights and so-so displays and get what I wanted - probably even enjoy the experience. That's not the case though, and I'm usually pretty irritated by the experience before I even get to the Walmart greeter.