Android security updates

Hello!
I am curious as to why android OS doesn't get security updates as fast as windows 10 gets them (if at all; i.e. older devices). Why is it that my 10 yo PC can still receive updates almost every other day, while my 2/3 yo phone is still stuck with a security update from May 2017? What is preventing android from being as updated as windows 10 is?

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