I think in Turf Wars, Splat Roller is arguably the hardest roller to use along with Carbon Deco. The nerfs were pretty fair for the Dynamo IMO. What's not fair is how the other rollers got nerfed as collateral.
What they did was make it such that you have to hit with the center of the roller to get the OHKO. For the flicked ink I agree with that change, but now even when the Splat Roller physically hits the opponent on the way down, if you didn't touch them with around the center 1/3 of the sponge itself, then you wouldn't get an OHKO.
So what the Splat Roller has become in close quarters is a poorer Carbon since a Carbon takes half the time from swing to splat (12f to be exact, Splat Roller takes 24f) and moves faster while rolling too. It's also why you're more likely to see Carbon Rollers (and both Dynamos) in TW than Splat Rollers (that's been my experience).
Also, the meta in Turf Wars has reached a point where you're unlikely to squish anyone with a roller unless you're playing with newbies. That means all 3 roller variants are going to get kills mainly by flicking. Dynamo is fine because the range is great so aiming for the center is totally justified. Carbon has always been designed to kill via flicking + subs.
Splat Roller has become the odd one out and most savvy players have realized that so you rarely see it used in TW. When you do see them, most likely they're Hero Rollers (people who just got the amiibos recently aka newbies) or newbie Splat Rollers under level 40 (very obvious they don't know what they're doing when you watch them play in game).
Maybe 1 out of 10 or 20 games will you see a Splat Roller who actually is good with it. The other times you'll see a 'Splat Roller' is the Krak-On variant which is still highly viable mainly because of its loadout. Even then it's still rarer than Carbon from my experience.
With all that said, Splat Roller still has a fantastic place in ranked thanks to it's loadout and the fact that in some modes enemies tend to be close together which actually makes squishing 2 or 3 in a row a very viable tactic.
And yes, I've also noticed how the game loves to group the same weapons together as a team. So finding myself with two other rollers is a very common thing or finding the team with 2 to 3 E-Liters is also another common thng. They really need to reprogram the algorithm to not do this so often.