Since the question was for superhero play the real limiters are what the GM is comfortable with especially if they have Caps, whether hard or soft on active points and combat values. Buffing characters are for the most part an artifact of MMORPG'S and not really represented in the core source material - comics. Blue Lanterns are the exceptions not the rule.
Remember that the job of a GM in creating npcs and deciding power levels for encounters is already a balancing act without buffer PCs. Some GMs want to focus more on good story than variable combat algebra.