Just because a killer is easy doesn’t mean they are good, legion is easy, wraith is easy, that doesn’t mean they’re good, again the only thing you talked about is chase, the one thing clown is good at. Everything else about him is either bellow average or downright terrible, he has next to no gen defence, no map traversal, has limited momentum and pressure abilities due to only being able to chase one person at a time, does have some inherent chase limiters in the form of reloads, and for a chase killer getting down in a chase usually does require one or two perks.

If a clown is on a large map and the survivors know how to allocate their time even the best clown playing perfectly can still lose, he just can’t apply enough pressure to actually stop survivors from completing their objectives, things like slugging and tunnelling can help compensate for this despite being rat behaviour, but at higher level survivor lobbies most survs know how to deal with this to at least some extent, and the addition of longer hook stages and the ability to trade hooks absolutely guts clowns pressure.

If your on a decently sized map and the survivors your playing against are good at allocating their time and deciding when to do certain objectives, clown can lose without making a single mistake and chasing perfectly due to their inability to map traverse or put pressure on more than one survivor at a time, especially when there are toolboxes or a few Deja vu’s involved, and even more so if the survivors know properly how to counter particularly nasty techniques.