Well if we disregard third parties, then both the PS4 and XB1 has had similar droughts. XB1 has probably had even worse ones.
I think what the OP is trying to get across is that something is usually announced for PS4, even if it doesn't have a release date or is 5 years in the future. Example is Naughty Dog alone:
TLOU: Announced Dec 2011, released June 2013
Uncharted 4: Announced Nov 2013, released May 2016
TLOU II: Announced Dec 2016, releasing May 2020
Other games from ND or Sony studios fill in the gaps, so there is always a big game to look out for.
While for Switch, we have no idea what is coming 2020, 2021, 2022 etc.