Shouldn't it actually help, seeing as the domain name is the important part? Now users can't get tricked into interpreting the path as part of the domain name.
Even if it does help in some cases, it's hiding the path, which in itself could cause other vectors of attacks. Just host malicious pages on legit sites where you can host and phish for clicks to it, faking the home page look and feel.
While I don’t welcome hiding full URLs at all and won’t use any browser that doesn’t allow to turn that off easily, this matter is more or less orthogonal to phishing.
If domain-owning organization fails to prevent a third party from hosting a phishing site under a path or a subdomain, that third party is likely well-positioned to deface the existing pages. With a subtle alteration (scripts that capture credentials and transmit them out), the existing pages grant an attacker all of the users with no extra effort—as opposed distributing a link to a fake page, convincing the user that the page is legit, and in the end getting a fraction of the user base.
For phishing to work you need a similar domain if you want to maximize the conned people. Copying the path from the attacked website is the easiest part.
I can even argue that if you take away the path from the URL, then it's actually easier to spot a phishing website since all you see is the domain if you don't hover over the address bar.
This change visibly hides subdomains. On some domains subdomains represent different sites from different unrelated authors. That being said it is of trivial effort to clone a site to capture sensitive information hosted under any subdomain with a valid HTTPS certificate.