IMO, blades are not that much "harder" to hit than cavity backs, that is, they are no harder to swing correctly and to put on the ball than CBs. They are a bit less forgiving, but we’re talking about maybe a 5 percent difference with a SLIGHTLY off center mishit and that’s assuming EVERYTHING else was perfect, ie path, face angle, clubhead speed, release. A cavity backed club is not going save bladed shots, fat shots, open faced shots, OTT moves, shanks, chunks, etc. which are MUCH more common than slight mishits. Blades WILL make you feel it when you hit thin, though.

When the pros DO miss, they barely miss. They can really take advantage of the forgiveness in a CB iron on the occasional slight mishit. Pros who can live with a percent or two error on the VERY RARE occasion of a slight mishit, may choose to trade a bit of forgiveness for a bit of workability and go with blades.

A more radical "game improvement" CB irons CAN give you a higher ball flight (and thus more distance) than a blade (or regular CB) on good shots, so there is some advantage in these clubs for slow swing speeds, but again, you have to be able to get the club on the ball.