Blobs, a distraction? Go fight a cruiser or destroyer with no shields, on some mode other than Easy or Very Easy. They are deadly to fighters. The issue is not how useful blobs were, the issue is how useful the alternative to blobs was:
No shields, no beams, no flak guns... It's a miracle we won the great war.
Until one faction had shields, the others didn't need them. The Shivans' shields were an advantage against the GTA and PVN in the Great War, but who are the Terrans' and Vasudans' shields an advantage against in the second Shivan incursion? Nobody. There aren't any factions in FS2 that lack any of these technologies.
They were good enough against fighters, and as long as the enemy warships weren't good against your warships, your warships didn't have to be good against theirs.