Scarlet Spider's "fail case" is using its basic abilities. 2 thwart and a chump block for 4 ER is not great.
Where Ben shines is sucking up the consequential damage from your Web-Warrior allies, and providing them with extra uses over several turns. Extra uses of Spider-Man/Peter Parker, and extra blocks from Spider-UK/Billy Braddock are particularly valuable, but don't overlook extra uses of Spider-Byte's and Madame Web's Thwart of 2,