Hi, I work at Riot anymore.
Mostly, we weren't community engagement people to begin with, we're just devs trying to make a great game. It's never been a Riot policy to force us to engage, but instead we simply wanted (or continue to want) to. I will say, personally, that engagement with the League community can be very rewarding but also extremely tiring and disheartening at times. Candidly speaking, it's ultimately just not the core of my job as an individual dev at all. Doing it too frequently is also not great for mental health, at least for me. I tried the Twitter thing for a bit and will probably continue to try it on occasion, but it quickly became too much for me because it was entirely direct interaction from a huge number of people rather than being able to jump in at will.
I know as a player of other games I really appreciate when the devs come out and talk about stuff, from the serious to the not-so-serious, and it gives me confidence that they're in tune with the community. Being on the other side of the curtain, though, it's also clear just how little reach we actually have on any individual platform, and how few people we're really enlightening or reassuring with each post. It's also become clear to me that the designers around me never stop thinking about players and read basically all of these posts, and usually don't comment simply because they don't think it will be productive or worthwhile. I still try to do it from time to time when it makes sense, because it's nice to make a little difference and also just nice to talk to some of the more...reasonable players. However, at the end of the day, we're a global game, and if our goal is to engage with the community at large and provide information then posting on Reddit or Twitter or any other platform is way lower priority and value than getting out official posts and blogs that can be localized and circulated.
I would contest the claim that we've pulled back on transparency efforts. I think we're more transparent about some things than we've ever been, like the Yuumi article we just published, the efforts to make a player-facing balance framework, and things like the Life of a Patch campaign.