Sure we can. If we treat "end-user" as someone who has no need to buy a domain, we can treat that as distinct from registrants.
It's trivially easy for me to think of friends and family members who will never own domains, and that's in the rich world. I've also worked in refugee camps where Internet is crucial yet nobody even thinks of infrastructure, let alone domains, and all access is through apps so the DNS isn't even relevant to them (Apps could be talking to cloud-based servers using fixed IP addresses or random-string domains for all they know or care).
It is our task to separate end-users from registrants for the purpose of determining their interests. Registrants have many other voices within ICANN, Non-registrant end users have no other path but At-Large.
This IMO is an absolutely bogus argument.
EVERYONE in ICANN is also an end-user, from the most vested and corrupted interests on down. In fact, I famously recall a head of a large registry who routinely trolled the NARALO list, and when called out protested that he was an end-user like the rest of us.
We do not need to defend registrants, half of GNSO already does that. We are uniquely tasked with speaking for those who are completely outside the ICANN food chain. If we are incapable of finding a distinct voice, that's on us.
- Evan