The ordinary people didn't have any relation with the world of ability users. This is true. But the ability users were once ordinary people too.
Ainsley couldn't just ignore the ordinary people, not to mention that the number of ordinary people in this world was larger than ability users.
Although the ability users ruled the world, the citizens were still ordinary people. The ability users also needed the ordinary people in their life.
A guild is a powerhouse with the best image in nary people's eyes.
When ordinary people awakened their abilities, if they came from ordinary families, they would immediately think of joining a guild.
Of course, they had to awaken the suitable ability to join the guilds. Otherwise, they couldn't join even if they wanted to.
Most ability users who couldn't join guilds would join powerhouses leaning towards the government because it was usually the safest and didn't endanger their lives.