Heh, Switch has the top 19 spots. Just one game at #20 prevents a clean sweep of the top 20.
You know sometimes when the hardware sales go down, software sales can continue. We can even get situations like Just Dance 2020 selling on the Wii even though it's been discontinued for years. But right now...the Japanese just aren't playing the PS4. Almost the whole country has moved on. At this point they are just looking for what else is going to be released on Switch.
New releases were still quite competitive between the PS4 and Switch until the (1st party) big hitters released for the Switch. And this is with a higher install base and a very active userbase.