There is the Recency Illusion to consider but I think that in this case you're probably right. There was a time in the Victorian era when people were going all txtspk, so to speak, but I think it was limited to expressions where the name of the letter substituted for a syllable in the word being textspoken, e.g., XLNC for 'excellency'.

Then there was the '20s or '30s little byplay:

FUNEM?
SVFM.
FUNEX?
SVFX.
OKMNX.