Exhibit A - Switch is the successor to both the Wii U and 3DS, and it's selling slower than its predecessors
Well, people buying two different platforms instead of one does a lot, not to mention families buying two or more 3DS per family. Doing that with the Switch is harder, though Nintendo is already working on that.
Exhibit B - Nintendo continues to make smartphone games and their new CEO Furukawa wants to grow that business
As much as I don't like to admit it, mobile nowadays makes too much money to simply ignore. It is not outright replacing Nintendo's main business, it is too volatile and unstable.
Exhibit C - Nintendo's stock price has dropped by approximately 25% since March 2018
Investors do weird things constantly, their attitude is not a direct response to the Switch. They just want more sweet mobile money, and are displeased they are not getting it.
Exhibit D - The 3DS was a better portable than Switch is
Well, this is true. For now, until Nintendo makes a revision that solves the problem.
Exhibit E - The Wii U had better third party support than Switch
Nope, and also irrelevant. 3rd parties didn't sell on the WiiU, whereas they do on the Switch, which means they will keep coming for as long as it is profitable to bring it over.
Exhibit G - The best Switch games are Nintendo games
What Nintendo system doesn't have their best games being Nintendo's own catalogue?
Exhibit H - Online multiplayer has been put behind a paywall on Switch.
This is shit and all, but if the rest are doing it, it is unfair to critisize Nintendo as a special case. This is the whole industry's fault.
You know it deserves the GOTY.