I am using WordPress with Yoast for my SEO. I have ran a few pages through SEO scanners and one of them has come back to say that my site does not use the meta keywords tag. I looked into it and it seems like this would be a really important tag to have on my website for SEO as It will let Google know what my keywords are. Should I sort this out or is there no point anymore? Does Google still use the meta keywords tag?
No, the meta keywords tag was discontinued a long time ago. Any tools that suggest you implement it are massively outdated. The tag was abused and became highly ineffective. To make matters worse, for those who used it correctly, your competition could clearly see the keywords you were trying to target for any page that used the tag. Nothing good really came from this tag and its removal has been a great thing for SEO