First, visible/invisible isn’t a dichotomic distinction, it is a spectrum. Stealth isn’t to make an aircraft “invisible” to radar, it is to reduce its radar signature, which means that radar can’t see an aircraft at all beyond a certain distance, and can make it more difficult to identify and track at closer locations. What that means is that a stealth aircraft can fly “in between” radar stations without being detected, where other aircraft couldn’t, and get closer to an adversaries location before being detected, and be more difficult/take more time to identify it as hostile and engage. That adds up to being able to strike many more of your adversary’s targets and escape without them being able to meaningfully engage you and gives you a significant advantage.

It is just like regular camouflage. You cant just throw on a camo jacket and walk around Walmart and be “invisible”. But in the woods, with the right camo, and the right technique, you can move very “stealthily” and if it allows you to get in a position to kill your enemy before they can see and kill you, that is the point.

Second, is an issue with AI I didn’t see anyone bring up. Related to my first point, stealth is about minimizing signatures and that that includes sending/receiving signals. Situations where an aircraft is operating in a highly contested environment means it may not be able to communicate reliably or safely and maintain stealth (they do have MADL but I am sure it can’t work 100% and maintain stealth perfectly). You would have to delegate complete shooting authority to the onboard AI. That is very difficult for many reasons, just one being accountability (who is responsible if an AI commits a war crime?).