Adding to the excellent points DannyHamilton made,  you're completely ignoring the problem of introducing a new node to the network. If the "genesis block" is rewritten and the history forgotten by everyone-- what basis do they have to judge the new system? You haven't provided a security objective/argument at all for that case. (Fortunately, as DannyHamilton points out, the original Bitcoin whitepaper addresses storage and does so in a way that doesn't make it unclear how a new node can be initialized. And Bitcoin core did 99% of the work to implement that storage reduction a couple years ago, in 0.8, it-- as mentioned-- just hasn't been a priority, due to the -- as mentioned-- linear growth maximum).

If you're feeling that the response here is a bit to blunt you should realize that this proposal (and it's ilk) has been repeated here many times since 2011, seemingly by people who missed section 7 of the white paper and seldom proposing something even as good as the design Bitcoin already has. While it's great that you're enthusiastic and have ideas, when you make a public post you're consuming the time of all the readers and people who respond to you. It's helpful if you describe the research you already did when you first propose something in a community that you're new to, since when someone seems to have missed something obvious (like the whole section on the subject in the project's whitepaper) it gives an impression that the poster didn't care for the costs they imposed on others.