I remember taking the sigils were huge faction operations involving several guilds and many boats plus lots of escorts. I don't remember sigil bearers being able to use moongates or have any convenience in travel. If anything they were hampered in many ways other than walking and thus the necessity for escorts. I also remember plotting out routes so that one escort party could meet with another escort party to form one big party.
perhaps you mean that they weren't able to use regular gates. "moongates" refers to the static gates that are by most towns. this is how sigils were always run on OSI, on every server, for the entire length of factions.