Nintendo Switch Online is an utter shit show of a service that achieves the miraculous feat of not actually justifying being a third as expensive as its competitors because it's not even worth that much.
It launched in September, without... any game to actually push it. Since then, we've had Smash and Pokémon presumably create more compelling reasons to subscribe to it. So, now, four months after launch, are you subscribed to Nintendo Switch Online?
None of these console services are good value and they're not even supposed to be. They're online play paywalls. Microsoft struck gold when they came up with this shit and now every console does it.
Which makes sense. They've got to improve and expand upon it before they can really draw conclusions out of data. It is still a very young service, after all.