The definition that the Anthropocene Working Group voted for makes sense from a geological perspective, but the conclusion that the mid-20th century marks the start of humans significantly altering the natural world on a planetary scale is probably thousands of years off.

Key example: humans caused the extinction of 54%-67% of megafauna in the Americas and Australasia on our arrival during the late Pleistocene. https://en.wikipedia.org/wiki/Quaternary_extinction_event

Since we're just another animal that perceive time on a biological scale, not a geological one, the definition of these epochs is more academic than practically useful.

If you happened to be curious about the other 11 sites they considered the information is here[1] on their, imo, really cool website.

1: https://www.anthropocene-curriculum.org/the-geological-anthr...