I use GREATEST_MAIN_BEGIN and GREATEST_MAIN_END so that people can put other things in main, around them. Also, there are often several RUN_SUITE calls, and I can't depend on vararg macros portably without also depending on C99. While there are some ways to work around that, they don't deliver enough value to justify the added complication.
Had it been possible, it would definitely make sense to add this oneliner utility. Since it would end up being very limited, it probably doesn't.
SUITE_LIST(suites) {
suite1,
suite2,
// ...
};
GREATEST_MAIN(suites);