You realize elementary has created the entire Pantheon desktop environment, right? So, "It's just their desktop environment with their stylesheet, their apps, and the AppCenter ecosystem," is basically what you are saying. In which case, yeah, that's exactly what elementary OS is.

`It's basically just ${desktopEnvironment} with a custom skin` can be humorously used for 90% of popular Linux distros but it's not really fair for any of them.