For wall penetration/distance, it's because 5G has better spectrum allocation and allowed transmit power than WiFi. For speed, it ultimately boils down to that

For wall penetration/distance, it's because 5G has better spectrum allocation and allowed transmit power than WiFi. For speed, it ultimately boils down to that massive, expensive antenna array (up to 256 antennas) enabling a higher practical spatial stream count than the 2-4 antennas typical WiFi base stations use to talk to client devices. (2x2 is effectively the standard for WiFi clients; a 4-antenna access point can theoretically talk to two 2x2 devices at once, with lots of caveats. So even your Eero is likely to dedicate its 4x4 radio to backhaul and use its 2x2 radios for talking to clients. Which then means users are less likely to see any benefit from 4x4 in clients, so no one makes them, so access points keep optimizing for 2x2 clients, and on and on...)