This seems to be a solid summary of this classic debate:
https://www.searchenginejournal.com/subdomains-vs-subfolders-seo/239795/
My personal issue is the following, with madeup example:
say we have
www.corporatewebsite.com
and its a company website with strong backlink following, but the ony content on the site is company story, career pages, and a very light blog. lets say this company is going to create a corporate web design service. for branding purposes, the marketing ppl want to create a brand new domain called
www.dopedesign.com but the SEO guy pushes back and says we should create a landing page on the existing domain bc i has many links pointing to it and is more ready/ripe to receive leads via google traffic, whereas the brand new website will take ages to really rank well. however, now the SEO person is faced with a question - do they create
www.corporatewebsite.com/dope-design or do they create
www.dope-design.corporatewebsite.com ? the former has more links/equity to put to use, but it also strays from the website topical theme. whereas the subdomain is more authentic bc we want to tell google 'we understand that this design service is a bit different than the content/topical theme of our current
www.corporatewebsite.com therefore we are going with subdomain.
but now my question goes back to square 1: if we are foregoing a subfolder in favor of a subdomain in order keep google happy, isn't the link power/equity that we are giving up by creating a subfolder a waste, since at that point we might as well create a new domain? TLDR: how much more equity/ranking power does a subdomain have over a brand new domain?