Spam in blocks is dealt with by having the spammer pay a high(er) fee for it right? This should be the effective discouraging system against spam Adam came up with...

And for miners the blocks could be filled with "spam" for all they care. As spam can also be defined as everything you don't care for, like for instance all other payments by others to others...

If a miner is prepared to pay the bill for the electricity, but does not find a block, the energy was not wasted/waste. Like when a gamer is prepared to pay the electricity bill to play a game, the energy to make that possible was not wasted.

If a "spammer" is prepared to pay the fee for adding data to a block, it is no different from being prepared to pay the fee for adding meaningless transaction to others to the chain, also recorded by one's full node.

Is essence the HDD on one's full node is already a dump of data useless to the individual except for their individual transactions. And all of the "useless" data was paid for trough fees, otherwise it would not have ended up in a block and miners would not have given it any priority.