Technical question: why was sending bitcoin to ip adresses abandoned?

In one of the early emails to Mike Hearn Satoshi writes:

Satoshi Nakamoto satoshin@gmx.com
Sat, Apr 18, 2009 at 10:52 PM To: Mike Hearn mike@plan99.net

[...]

Transactions sent to a bitcoin address will always say "from: unknown". The transaction only tells who it's to. Sending by bitcoin address has a number of problems, but it's so nice having the fallback option to be able to send to anyone whether they're online or not. There are a number of ideas to try to improve things later. For now, if things work out like the real world where the vast majority of transactions are with merchants, they'll pretty much always make sure to set up to receive by IP. The P2P file sharing networks seem fairly successful at getting a large percentage of their users to set up their firewalls to forward a port.

[...]

Source: https://plan99.net/~mike/satoshi-emails/thread1.html

So he considered sending bitcoin to a bitcoin adress a 'fallback option' only, with a number of problems (?) and the vast majority to be set up to recieve by IP.

Why was this, and why was this abandoned later? Can anybody eli5?

Many thanks in advance.

Submitted March 21, 2020 at 02:53PM by Rattlesnake_Mullet https://ift.tt/3a9SZWk