Welcome!
Please check out Van Canna-sensei's Forum. There you will find an excellent post on blocking that Roy Bedard-sensei originated a few weeks ago (you may have to set your screen to look back 20 - 30 days).
You ask about why Western boxers do not block, but under scrutiny, of course they do.
In fact, boxers are the absolute best at what I call the "non-block": Slipping punches, "squashing" punches, parrying punches, and just generally making you believe you hit them when in fact you did not.
Next time you watch a boxing match on TV (you'll need slow-mo to see this), check out those barrages the crowds seem to love so much. Then look again in slow-mo. 90% of the "power punches" you see never hit their mark and the ones that do are often deflected, slipped or otherwise "neutered" by expert "non-blocking" and body movement.
As Roy-sensei points out, formalized blocks should be practiced, but not relied upon in real "combat". There you will need to react much more quickly. Your parries, slips and "squashes" will do you well.
...You are practicing these, right??
Keep training!
Gary
