Yes but in November 2015, it had no competition and won almost all three regions with ease. Its grip has slipped mightily since then. If you aligned sales between Switch and PS4 since Switch launched and looked at marketshare it's a vast slide for Sony compared to Wii U and PS4. So it's "peak" as far as year-to-year marketshare is far, far over.
Your logic is a bit ilogic. PS4 is about to have its best year ever in terms of sales, why would Sony care if the Switch sells better than the WiiU or if the XboxOneX helped MS push some extra boxes ? All that matters for Sony is that the PS4 is still selling like hotcakes 4 years after its launch and it looks more and more like it is gona end up with PS2like numbers by the end of its lifecycle, wich is just insane on this day and age.
Also if the PS4 has more ocmpetition now than in 2015 and it is still selling more than it did back then, thats even more amazing.