It's only recently that single malt whiskies have been popular. Until the 70's most whiskies sold were blends like Teachers, Famous Grouse, Chivas Regal etc, but now the marketing types have realised they can sell the main malt from the blends separately, usually at increased price.
I've recently discovered this little gem of a malt from Glenrothes - click here - which for decades has been used by Berry Bros as the base of some of their blends, but is now being widely sold. I think it's just passed 15yr old Glenfiddich as my favourite tipple.
The great advantage to blending is the ability to maintain a consistent standard of taste.
Lots of whisky drinkers don't realise that single malts are blended, but they are - distilleries produce small batch runs, and then blend them to achieve consistency. Even blending doesn't eliminate variations in single malts,although the bigger distilleries have more batches to blend from, and therefore more chance of achieving consistency.
Probably the biggest difference in drinking whiskies in the last 50 or 60 years is that they used to drink a 'whisky and soda', which is why the older blends tend to be quite fiery compared to the ones drunk now with little or nothing added. Hague was a particularly fiery one that you never see now. Don't be 'vague, ask for Hague' was the selling line.
Yes it is. "Single Malt" is a blend of several batches from the same distillery, they're then watered down to the desired strength (40% is usual, older malts are often 43%). Some distilleries release Single Barrel malts that are just that. These are usually in the 50-65% region.
I once visited the Four Roses distillery in Kentucky and their blender takes bourbon from up to 15 casks in three different warehouses to make the Yellow Label product.
"Blended whisky" is a blend of malt from several distilleries, and the likes of Bells, Johnnie Walker et al are keeping many small distilleries alive. Some whisky never sees the light of day outside of blended scotch, and this is a real shame, although Gordon & MacPhail of Elgin buy up barrels from small distilleries for private bottlings and there are many delights to be found in their shop on South Street in Elgin