"The nature of Bitcoin requires users to run fully validating nodes, necessarily involving downloading, storing, and transmitting every transaction, even if they are fake/spam "transactions"."

"downloading, storing and transmittting every transaction" - this is untrue.

"downloading and validating" - this would be true.

https://github.com/utreexo/utreexod

utreexod is an example of a fully validating node that downloads and validates but does not cache (store)
and need not retransmit every transaction.