Yeah, it's amazing. We've had decades of improvements in hardware performance, only to end up with software that's slower than anything that came before it. Yet apart from a small minority, nobody seems to bat an eye.
Even my mum complains every day about it. "Can’t be that a 4 year old smartphone can’t run a chat app like whatsapp fluently"
But she refuses to buy a new phone, because that would just fuel this even more.
I see it myself, upgraded from Huawei Ideos X3 (2.3.7) to Motorola Moto G (5.0), and it’s just as slow as the old phone was. Despite being twice as expensive.