Wikitree was never meant to be a matching service.
1 - Wikitree is very much dependent on correct genealogical connections, and as long as those profiles are connected and sourced correctly,...
2 - The global tree shows some potential and possible matches there may be out there. But these are not definite matches. For potential matches, you and the other person would have to do a DNA test, or at least match up your DNA data, on Gedcom, if your tests are not with the same company.