This actually doesn't surprise me. Valve is getting greedy.
But; to be clear; by using these tools, to unlock the DLC without paying for it, you are cheating in the game. That's a mere fact; and not a moral judgement of anyone choosing to do so.
Personally, I don't judge anyone for doing so; and would use these tools myself if I thought a DLC were too predatory, expensive or otherwise unfair to not have it available.
That's not saying it's fair or right for Valve to do so; nor is it saying the VAC bans or account suspensions are deserved. If you get hit by this; you absolutely should pirate every title you already own/purchased via Steam right away, and pirate anything else you want in the future.
The only way to make them regret doing things like this is voting with your wallet; and asking others to do the same. Stop spending money on Valve. Once their earnings fall they'll be forced to hear people's concerns.
Sure those exist, but is there anything like a mod manager that works for those sites? Imagine having to manually manage your mods/addons for a game like Cities Skylines. When I played, I had well over 1000 assets installed. There's simply no way that would work.