the on-chain footprint of coinjoins is much more obvious. blockchain analysis heuristics based purely on common output sizes are unlikely to be very useful.
Not only the output amount. How ChipMixer creates the chips follows certain patterns, you need to emulate the patterns too. Just splitting your coins into ChipMixer's chip sizes in your own wallet won't help against analysis like the FAQ claims. It can only fool stupid analysis tools.
There are more problems. Many users sweep different chip sizes in single TX making it even more obvious. Even if none of these worked, then chips will lead to someone's tainted coins and will raise alarms at the exchange etc.