I know! It’s just not very obvious, especially to a new user not familiar with Discourse.
The fact that it is hidden actually exacerbates the issue, because the user can spend considerable time (as much as a minute or two) looking for a reply button thinking that they just aren’t seeing it instead of moving on or creating a linked topic to discuss whatever it is they wanted to talk about.
The example above even goes a step further by giving a second line (Also in the screenshot) that says “No replies to this topic” for the absolute newbie in case they don’t understand what a locked topic is.
I dunno - I just think it would make for a better user experience for the newbie - maybe I’m wrong?