tbh i use keywords meta tag cuz they are pickable from GSA.
what else, other search engines still pay attention for meta keywords= they rank u higher
what else, a lot of other kind of crawlers like these from ahrefs/majestic or whatever will use search engines like bing or yahoo. obviously they will discover u first if your page is closer to top 1.
now this is nice because that counts as actual backlink! and google sees that
apart from that, putting keywords in meta keyword tag also is crawlable by google bots. Maybe it doesnt have any influence directly, however the ratio of keywords to code is bigger.
page text to code ratio is important factor. i believe this includeds stuff in <head>.