Yes, some top schools are less open to funding MS students than others. Speaking from experience, other schools (including top 10 schools) are just as “funding-friendly” to MS students as they are to PhD students, particularly when it comes to TAships. Nobody here has denied that. Furthermore, as others have been saying, RAships are generally between the student and the faculty member. You would have to talk to potential POIs to find out if they a) have funding for additional students and b) if they’re willing to fund thesis MS students.