This can be overlooked if you send fiat to a bank account because, even if the account is dormant, the benefactor can reach out to his bank to get access to the money. However, if it is Bitcoin and it happens at an address that one is no longer using, maybe due to the loss of the seed phrase, the asset is gone forever. In a non-custodial wallet, when the seed phrase is nowhere to be found, there is nothing that can be done about the asset. It is very important to always reach out to the person to whom you want to send funds because, in cryptocurrency, it is common for people to create a new address for different reasons.

As for me, I don't just send funds to someone's address simply because my counterpart and I have done some transactions; I always ask for the address to avoid mistakes on my end.