Why not? Who doesn't want a raffle, especially if it is free raffle? Setting up free raffle here in bitcointalk is cool way to involve the community without them needing to spend any cryptocurrency. You can giveaway prize and let people join by leaving post or comments on your thread or by doing something like sharing the post on social media. Just be sure to explain the rules and who can enter and follow the forum's guidelines to avoid any problems.

Don't be like this: https://bitcointalk.org/index.php?topic=5487095.msg63738537#msg63738537