Besides that, Apple talked about how hard it is to be “HDMI 1”. Especially now that all of the TVs have “smarts” and most people still have cable. Not to mention that an Apple TV is $149-$200. I have two ATV4Ks that were both free when AT&T was doing their deal. We don’t even use it on one of our TVs that have Roku built in.
Besides that, sales before 2015 are almost irrelevant. That was before it had an App Store. A lot of the new streaming services don’t even support it. Roku wasn’t being integrated into low end TVs left and right.
There is no better experience for most people than a TV with Roku built in. One remote controls everything.