Correct. Thanks to Carbon Copy Cloner and my backup strategy of having an identical pair of storage devices, I fresh-installed Mojave 10.14.6 on storage "A" (APFS, no choice there), migrated all data from storage "B" (which uses HFS+) to it, then used CCC to copy all files back to storage "B" (including System files). Then re-formatted storage "A" as HFS+ and re-copied all files back to it from "B." Now both Samsung 970 PRO SSDs contain bootable copies of one another on the HFS+ filesystem. Mojave boots in 19 seconds with no "TRIM" problem.
I also did the same for my High Sierra (10.13.6) installations.
Except for your specific SSD issue, APFS is far from being a bad filesystem — indeed, I wish I could use it in 10.9 too...

It brought some advantage from ZFS (which I still use, by the way).
Where I don't agree with Apple is their shambles of current OS structure (Preboot, Recovery, SSV, etc.) It partly makes sense (separate volume for the VM) but what a waste of usable space!
(I've read somewhere that it's not necessarily a bad idea to format external backups as APFS...*)
If we think of the early days of Operating Systems, it was just a minimal interface meant to run programs, now it's a mastodon full of useless stuff (well, if you don't own all the outfit of iThings...) and apps like Safari that are no longer updated after a few years (if you stick to a given version of the OS).
All this to say that I'd be happy to stay up to date, but every time I read the specs of the latest MacOS, I just think "What for?"
*EDIT: one of the many interesting articles from ELC
APFS backup disks offer different possibilities for adding volumes for your own use, alongside the backup volume. How do you decide what’s best?
eclecticlight.co