Do WordPress Page Builders increase page load speed and as such, should these be avoided by those competent at hard coding?
Or is there something else that I am missing as the only real value, I can see with Page Builders, is that they help reduce time spent on coding.
Use code. Page builders add additional load time. Your site may also become less portable and maintainable because a bulk of the design for your site could be stored in the database. It really depends on the situation. I would assume code to be a little cleaner though.