Nah, Turkish and others here have made it clear that it's fine to just mush all the numbers together. A mere 150 million PS4 sales would represent stagnation for Sony's install base since last gen.
Maybe because they see NS as a "mushed" concept. If NS is the successor of both the WiiU and 3DS it's just natural to sum home console + handheld sales on each generation.
PS4 was not the successor of both PS3 and PSP. Your comparison makes no sense.
As for the "Sony's stagnation" that's just false. Who did you see here calling stagnation if NS sells 250M (Wii + DS sales)?
Prediction made in 14/01/2014 for 31/12/2020: PS4: 100M XOne: 70M WiiU: 25M
Prediction made in 01/04/2016 for 31/12/2020: PS4: 100M XOne: 50M WiiU: 18M
Prediction made in 15/04/2017 for 31/12/2020: PS4: 90M XOne: 40M WiiU: 15M Switch: 20M
Prediction made in 24/03/2018 for 31/12/2020: PS4: 110M XOne: 50M WiiU: 14M Switch: 65M