Agree with Deanohh... if you're doing it smoothly, you're probably doing it right. You may not even realize you're doing anything "special."
Blips are only necessary if you need to change the RPM quicker than it would rise at the current throttle input level. You can over-shoot a rev match pretty easily with an overzealous "blip".
Rev matched downshifts are necessary so as to not cause excessive surges of braking force at the rear tire, which can unsettle the rider and bike.
You don't want to be "dragging the engine back up to speed" by "dumping the clutch" or "slipping". You want the engine to advance to the speed that the next gear down will engaged at.
Clutch, Rev match, shift/clutch, roll off. Repeat if necessary.
It happens so quicky, it's all one motion.
 Rev matching can include a blip or not. It all depends on the specific situation at the time of application. I.E. for a 3->2 change to happen at the same speed as perhaps the 4->3 change (depends, were you under power in 4 before the downchange to 3? -again, it is situational). Reason being, if you were under power in 4th, and made a decision to downchange, you could easily match with little if any input change on the throttle. But, after the roll-off back to idle position through 3, you no longer have a condition where the engine will accelerate simply by pulling in the clutch. To rev match, you will have to add power between the time you pull in the clutch and before you let it out. The 3->2 change is a much bigger jump in gear ratio than any of the higher gears. To make it happen in the same time (more RPM range to cover to split the gap) a blip, rather than a gradual roll on of the throttle, is more expedient.
I don't care one way or another if people "blip" or coast or rev match their own way, or what... but I sure do grit my teeth when I see people use the clutch as a brake- and that's NOT what engine braking is... Again, such a method will either add unnecessary wear to the engine (slipping-drag-up), or cause such a such a sudden surge in rear wheel braking force (dump-drag-up) to possibly unsettle the bike.
And engine is an air pump that can either drive a load (fuel/spark, pushing the bike) or be driven by an outside force (bike momentum). It is an effective brake because when you roll off the throttle, no more fuel is used, the throttle butterfly closes, and then the engine is drawing against resistance, building a vacuum. None of this wears the engine significantly differently than when fuel is applied and the "pump" is pushing the load instead of being driven by it.
Yes, Keith Code says brakes are cheaper than engines. They are. Your call, I'm just saying to those who may be doing it- do it right, for your own safety and the longevity of the bike. If not, you're better off coasting down w/ brakes.
[insert obligatory forest gump quote here]