The teem "ineffective" in your first premise provides a clue to its faultiness: it embeds a negative into a key term, and when this term is unpacked, we discover that you are really assuming a universal negative: namely, that there is no other purpose beyond the one you identify as ineffective. Proving a universal negative is, of course, really difficult, and a semester of philosophy might teach you this.

Do you really prioritize fleeting ram use over permanent disk storage? That is a silly priority to have.

You will store the "spam" anyway when it gets mined. But you already know that. You will not stop others from using Bitcoin the way they want. Enjoy your pure mempool.

Ram is more precious than disk space, that's why 1tb of ram costs way more than 1tb of disk I prioritize efficient use of the scarcer resource

Blocks are persisted to disk, which is abundant The mempool is stored in ram, which is scarce Therefore spam is more harmful in the mempool than in the blockchain

I prioritize eternity over fleeting.

You clearly don't understand cost and the multidimensional status of things. There's more than just one kind of limitation.

If you store "spam" in RAM until it gets mined you avoid having to redownload and cryptographically verify the "spam" tx once it gets mined into a block or it is broadcasted to you by another node. That saves both bandwidth for downloading and CPU for verifying. I would not agree that disk space is abundant. You can get by with just 300MB RAM for an unfiltered Mempool and don't have to upgrade RAM however many noderunners will soon have to upgrade from a 1TB SSD to a 2TB one which is a cost factor and also implies manual effort and downtime.