To be brief, #questions-and-help uses a text channel format where anyone can jump in at any time - this is by design, so that people can (in theory) get answers as soon as possible; whether or not those answers are accurate and correct is a separate issue, though our staff (new player mentors, global moderators) has been trained to remove obvious misinformation so people don't get confused.
Discord as a platform made this the easiest avenue for us to provide support for our users that go a bit beyond the capacity of Square-Enix customer support (think game knowledge, mechanics, and so on) - you have correctly identified #1116899335628668979 as a recent extension of our subreddit, of sorts, which will allow for a more individualized experience if people request that.
#questions-and-help is strictly moderated due to the volume of content we have flowing through that channel hourly, and allowing that to be entirely unabated with no form of restriction will result in no one really getting the help they're looking for, and our staff being less able to help when needed. The slowmode allows the staff to be able to better properly screen incoming messages (that still come in at a very high volume, mind you!) for misinformation as well as our other server rules - as others have mentioned above, this should also incentivize users (frustrating though it may feel) to put thought into the questions and answers they post there. There are alternatives if people don't want to use that (#beginner-lounge, #1116899335628668979, etc), but this channel is the most staffed and will have the highest likelihood of a quality response.
Please also do not mistake our "questions and help" channel as a form of in-game support - we are a volunteer community that is neither sponsored nor endorsed by Square-Enix - as such, we have chosen to use a method that we feel best suits our community given the tools available that the Discord platform provides to us. We have neither the bandwidth nor the motivation to iterate on what we provide our community, especially if the feedback leading to those iterations is not well thought out.
I will always appreciate criticism given to help make our community better; I ask that you please understand our reason for making this the way we did, and we understand if you seek other avenues if ours doesn't suit your needs.