Famitsu (a Japanese magazine) has top ten sales of console games in Japan every week. Until the Switch 2 launch, Mario Kart 8 was there nearly every week.
Wii Sports enjoyed a similar status, as it was also bundled with a console. I don't think console bundles are necessarily a fair way to count video game sales.
Mario Kart was not originally bundled with the Switch and the Switch has never been exclusively bundled with Mario Kart. You've always been able to buy a Switch by itself or bundled with other games - Mario Kart was not even the first bundle. It was like the 8th or something - two years after release, and has been re-issued every Black Friday since, but there have been numerous other bundles since as well.
A pro scene is absolutely not a sign of a popular game. Oftentimes it's the reverse. There are so many strange externalities with a healthy pro scene that can positively destroy your general appeal. Leaving you with perhaps 10,000 really insane players, and no community outside of that.
There's also a ton of multi sale per person in overwatch. Especially before role queue existed, it was easier to just spend 10 bucks on a new account to learn a hero than to suffer ELO hell while doing it. People are so toxic in competitive shooters, and playing at the ELO of your best heroes while on a hero you don't even know the abilities of is very very unpleasant. I struggle to think of a person I played with that didn't have multiple accounts, some with as many as 5-10.
This is to say nothing of the rampant cheating in the game, which if a person ever gets banned for, there is nothing stopping them from just spending 10$ on a replacement account.
It’s rare for any product to have more success in later invocations than the first edition, that is where the narrative is fresh and strong- and even in the event sequels are stronger, they tend to increase sales of the first season/movie/etc; because people want the whole experience.
There’s no fucking way they would have spent so much money on three WH titles and a fuckton of DLC to make an absolutely colossal RTS game if it was niche. Total War Warhammer single handedly saved WH Fantasy with how well it sold.
PC games are relatively niche compared to console gaming for one. And RTSes tend to be heavily PC biased from the control schemes. Although these days you should be able to keyboard and mouse to a console due to being USB or Bluetooth connected anyway, using it on a couch without a desk would be awkward.
Team Sonic Racing is also available on iOS and android stores while Total War Three Kingdoms is PC only. The price must also be widely different, so the sales numbers are complex to compare.