The answer of KaleMaster is unfortunately wrong. Yes, you need a internet connection to play Eco, even in Singleplayer.
Oh, to allow people with slow internet connections to play with minimal interference?
No, just that those are typically content mods, changing the game massively, which I do not like and is not very suitable for public servers.
There are a lot of servers using mods, but a lot of them use the same ones and there is a distinct lack of content mods in particular IMO. I find it a bit odd considering how easy such mods are to make technically.
Well, I'm not into content mods anyway :D
As a server admin I generally keep mods limited to stuff that needs no downloading, that's just a general rule of thumb for accessibility.
Interesting opinion. I actually get a way different view overall. It's like the majority of bug and crash reports we get have mods in it. It's not a majority using modded stuff, but it doesn't feel any particulary low amount from our side either.