During purine synthesis why does GTP activate adenylosuccinate synthetase and why does ATP activate XMP-glutamine amidotransferase?

During purine synthesis why does GTP activate adenylosuccinate synthetase and why does ATP activate XMP-glutamine amidotransferase?

My reasoning is that XMP-glutamine amidotransferase ends up making GMP which later on is used to create a high energy metabolite like GTP/ATP so shouldn’t have that a negative feedback mechanism on the enzyme?