Riot's been pretty proactively trying to bury Dominion for years. The player base gained momentum in the years over it's release. We had a pretty solid tournament scene going on for I want to say 3-3.5 years total. If you want to see the history of it nearly in full I suggest you give Gandair's Youtube a look since he's archived as much of it as he could.
https://www.youtube.com/user/VATOCLAN
But yeah, it's been a sad history of ill-hearted promises and some of the most passive-aggressive betrayals of customer faith a company has ever done. Riot makes Electronic Arts look like saints in that department. Not once, but twice the Dominion community had to make massive, month long pushes on the original forums, garnishing over thousands of posts and +'s just to get a Red to come on and say "Yeah, we lied, sorry."
They tried to pretend like they were going to pay attention, and for a while it looked golden. We got our own dev to do map specific changes, item balances, ect. And he was pretty proactively involved with the community...for about a month. Then Riot yanked him away once they saw things were actually being properly fixed and tossed a lower tier Rioter our way (not in an insulting way, literally just someone lower in the company hierarchy). Changes trickled slower and slower, outright broken things (see immediate post-buff Thresh) took several weeks to even be addressed. And all communication dried up again.
One more push was finally made with another massive topic and Riot finally came out and said "Nope, we don't care."
The community pretty much fled en masse after that. Tournaments died down. Forums changed to boards and Riot left anything Dominion related to languish in the sea of ARAM, TT, and Mode of the Month posts. So now all that's left is pretty much a small pittance of people who stick around just out of a mixture of spite and passion.
If you ever, ever see a Red post about Dominion it'll be because a topic like this somehow gets 300+ upvotes and I guarantee you it'll be nothing more than "Yeah, we screwed up. No, we're going to do nothing about it."
It's the same mantra they've been spewing since everyone realized they lied about the initial Ranked promise.