Granted, it does have restrictions, but I still don't see how it
couldn't absorb Amaterasu. As opposed to the surprised attack via exploding tags, Amaterasu's flames can be targeted once they hit Nagato
Also, for some reason Nagato's body was revitalized when he used Preta Path to absorb Bee's V2-powered Lariant.
Amaterasu doesn't have anywhere near the same chakra as Bee's V2 Lariant, but the basic concept should still apply. He was able to use the chakra he absorbed to some extent to heal himself. Although not his legs which is probably because they've been damaged for such a long time.
Am I saying that Preta Path's chakra absorption is to the same extent as Samehada? No, but the fact that Nagato's body healed when he took in a vast amount of chakra does imply that the chakra taken by him goes somewhere. And that healing his body is one possibility depending on the amount of chakra he takes in.
Who knows. This may even explain how Nagato still had the chakra to perform a Chibaku Tensei after such a long fight against Naruto. He absorbed a bunch of Naruto's attacks including a full Sage Mode Rasenshuriken:
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