Even without English doing something similar, as the video mentions, this is a lot like Indo-European languages insistently marking subject attributes in the verb:

• person - "I go" vs. "he goes" (English)
• number - "parla" vs. "parlano" (Italian; he says vs. they say)
• gender - "mówił" vs. "mówiła" (Polish; he spoke vs. she spoke)

Like, it looks like the inverse phenomenon, but it's actually the same thing - you're plopping info from one part of speech into another, because they're supposed to go together anyway.

oops, I typed in 'linguistics' and picked the comm from a drop-down menu