Why don't console manufacturers create their own game engines?

[Hephaestos]

Mr Khan said:

PullusPardus said:

Sony made lots of engines, but they only shared quite few (maybe just one if i remember)

Nintendo makes one engine per console, and they don't share it.

Microsoft on the other hand rely on third party engines , mostly Unreal Engine.

One per console only on Nintendo's part? I find that dubious...

yeah they used the same for luigi's mansion, windwalker and twilight princes.... I would have thought it was obvious from the identical look of the games :p

it's like wii sports, SMG, SMBWii and Zelda SS, same engine ^^