They’re one way functions. Encryption requires decryption, so you cannot lose information.

Hash functions are meant to lose information. They cannot be reversed. What they’re good at is verification; do you have the right password? Do you have a proof that this is your message and not someone else’s?

We already use hash functions where they make sense, but the parent is not entirely right; not all hashes and signatures are equals. Some are very quantum susceptible. Those will likely be broken real soon (think years, not decades). Some are quantum resistant.