The curse of Latin-y grammar
The Latin-worshipping tradition is responsible for the grammar elitism of infinitive splitting, proposition ending, and the singular “they.”
Robert Lowth, who wrote a widely used English grammar in 1792, passed an aesthetic judgment on the sentence-ending preposition (it wasn’t Latin-y enough), and later grammarians elevated this preference to a full-on ban.
By similar specious reasoning, they objected to infinitive splitting and the singular ‘they,’ despite centuries of prior English usage.
This is the same tradition responsible for adding a bunch of superfluous silent letters to words like “dete,” “samoun,” and “iland,” because “debt,” “salmon,” and “island” look more like Latin “debitum,” “salmonem,” and “insula.” (Never mind that “island” doesn’t even come from Latin, or that generations of schoolchildren would now have to go to extra effort. Many languages can’t have spelling bees because their spelling systems are so logical that no one would ever get knocked out. English spellers can only dream!)
Source: Gretchen McCulloch, Because Internet