Yes you can invent all kinds of workarounds for their core design. Re-implementing imports like you do. Or bundling, like everyone does and something that even lit recommends: https://lit.dev/docs/tools/production/
Except cache is not infinite, it is routinely expunged and re-fetched.
The "nothing burger" is so significant that even projects whose stance is "web components are the end all be all of web development" like lit recommend bundling.
And we're back to my original comment - imports get served from the local cache, so a bit of a nothing-burger in the great scheme of things.