Then they should add PS5 streams on PC-Plus and also enable streaming on any device (with capable network options and paired controllers). Everything in that regard is possible right now, just not unlocked yet.
Streaming did not shatter the gaming world so far, but allowing more devices for the same required server landscape they already did built, should be more cost efficient than having unneccesary roadblocks that prevent people from accessing the PS world. Kinda duh. People with the actual hardware at home are probably less likely to really need streaming as an option (PS3 streaming is still stupid, when I have my PS3 hooked up right next to it), but going after everyone not having Playstations should be sensible.