net.ifnames=0 dwc_otg.lpm_enable=0 console=tty1 root=LABEL-writable rootfstype=ext4 elevator=deadline rootwait fixrtc verbose
And still get the splash screen.
I had the same problem, after making the same change as you with the same (non-)result, but eventually resolved it... but I don't remember HOW.
Basically, all I can say is that yes, it's possible, but nothing more than that, sorry.
I have a vague feeling i just did a recursive grep for "splash" on the entire FS, and found one somewhere else in a file that the boot process was "secretly" actually using, rather than the cmdline.txt that you and I "incorrectly" thought it was. (I suspect it's another file that gets added to the cmdline.txt contents: the Pi boot process does stuff like that a lot).
I'll check my notes in case I wrote it down, but it wasn't until a few weeks after I'd finished setting everything else up that I finally tracked it down, so don't get your hopes up.