My understanding is that it's reasonably common for a chunk of agender/nonbinary people to use traditional feminine/masculine pronouns.
It just seems a bit more direct to ask how people want to be referred to; I would compare it to how typically in web forms we ask people if they go by Mrs/Ms/Mr/Dr/etc directly, rather than asking them if they have a PHD and are married.
Especially if we're talking about gendered languages where there isn't strong support for nonbinary pronouns/variants. Someone telling us that they're agender/nonbinary doesn't actually help us much in that situation; we won't know from that information alone whether to use feminine or masculine variants.
It just seems a bit more direct to ask how people want to be referred to; I would compare it to how typically in web forms we ask people if they go by Mrs/Ms/Mr/Dr/etc directly, rather than asking them if they have a PHD and are married.
Especially if we're talking about gendered languages where there isn't strong support for nonbinary pronouns/variants. Someone telling us that they're agender/nonbinary doesn't actually help us much in that situation; we won't know from that information alone whether to use feminine or masculine variants.