1- Thumbpulling/mouthguard/histo-stretching brings slower more sustained change that allows for the whole structure to adapt (including the periodontal ligament) so it doesn't create a gap, one of its benefits over expanders.
2- Expanders only expand in one plate (horizontal). The techniques I share expand in three planes: lateral, forward and upwards.
3- Other improvements I've gotten that expanders/surgery can't give you: Better posture, straight teeth, better symmetry, no complications (which are really really common with expanders and surgery, plus being expensive), etc.
5- Much older people than me have gotten a lot of results too. This is because even if others tell you otherwise, the scientific literature is actually inconclusive in when sutures actually close. Plus what I share works via soft tissue, I go in more detail in other comments and that video.