I keep catching myself attempting to reply to ancient posts in a resurrected thread (that appears in my New Posts list and that I had not read before, so starting from page 1)
I'd enjoy some sort of cobweb background or color distinction be added to posts more than 3 months old so I don't accidentally "Like" something from olden times.
Or make the date bold and red if it's old, maybe, so it's more eye-catching, to OP's point.
It's easy enough to color code the entire thread to be a certain color if older than a certain date. Just requires time, knowledge, and effort. Not sure any mods/admins have all three of those right now. Threads with the last post older than a certain date have a red box at the bottom of the screen.