How to play steam games without updating
Updating both the Game and mods can break your game and/or mods, when done automatically.
It needs planning and testting first to see what's changed, sometimes mods also require an update, due to changes in the game or even other mods.
If a mod is changed and is one, another mod relies on it, the dependant mod may need an update as well.
Game changes cause the most problems, because every mod relies on the game.
Generally the less experienced you are the longer you wait.
Other more experienced modders, will test the game for changes.
Then we use our chosen Mod Manager, to install that archive, like any other mod.
I agree with the OP though, Steam system is a good way to break a working modded game one is happy with.In the past, only running Steam in offline mode, would ensure no auto updates ran and going online, would start any auto-updates, as soon as you went online. I can at least check Steam for an update, without actually triggering it.The recent change to Steam gives you an online option now, it appears to work well enough, I see games listed needing updates that haven't triggered. Now you're in charge of Updating, when should you Update.New modders may not be aware of what makes Steam an awful Platform, whether you use Steam Workshop for mods or not.Experienced Modders may not be aware of the changes to Steam's update settings (Skip to Heading, Recent Steam Change).