But they do have High Elf customization. Relevant interview/source provided in the link.
And this is also suggested in another interview. It leaves enough open for interpretation. This has been circulating around the forums as well.
“They start out as a small group,” Danuser continues. “But it’s natural as other elves have found out about them — elves who are interested in new sources of magic, power, or opportunities — would see if they could undergo a similar process. They’re not … recruiting, necessarily, but they’re open to those who show a similar interest.”