I see no reason why we shouldn't have this and I would like to see it introduced if it can be done on SMF.

---

Alternatively, what you can do is scroll up to the first post. Copy the name of OP, hit CTRL+F followed by CTRL+V to paste the OPs username into the search field. It works both on Chrome and Firefox. Every mention of OPs name will be highlighted for you on the screen. After that, just pay attention to the left side where the usernames are written while you are scrolling down the page and stop when you see the highlighted name you searched for. You can also click on the up/down arrows if you don't want to scroll down manually. If the thread has multiple pages, click on the All button before.