why was block compacting never done?

i've seen this in the white paper:

Reclaiming Disk SpaceOnce the latest transaction in a coin is buried under enough blocks, the spent transactions beforeit can be discarded to save disk space. To facilitate this without breaking the block's hash,transactions are hashed in a Merkle Tree [7][2][5], with only the root included in the block's hash.Old blocks can then be compacted by stubbing off branches of the tree. The interior hashes donot need to be stored. A block header with no transactions would be about 80 bytes. If we suppose blocks aregenerated every 10 minutes, 80 bytes * 6 * 24 * 365 = 4.2MB per year. With computer systemstypically selling with 2GB of RAM as of 2008, and Moore's Law predicting current growth of1.2GB per year, storage should not be a problem even if the block headers must be kept inmemory.

is there some reason why that can't be done? the bitcoin blockchain, the longest so far, should only be 4.2MBx10 years = 42MB total?!

submitted by /u/I_SUCK__AMA
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source https://www.reddit.com/r/btc/comments/l0btg5/why_was_block_compacting_never_done/