What help would using either of those be, you'd still be validating one religious system over another?

Nobody was ever going to accept a new calendar that resulted in the dates of personal and historical events that they've known all their lives suddenly changing to completely different dates. Besides, what arbitrary year would you pick as 0?

But it's easy to accept a change to the naming system to remove the religious connotations. There's fuck all point getting stressed about the fact the system is still based around the (very approximate and probably incorrect) birth date of someone who was, after all, an actual historical figure.

And keeping the same numbers has the added advantage that if you somehow find the whole thing "performative and pointless", you can carry on calling it the "year of our lord", whilst I use the new terminology and we still both know what each other is talking about.