I figure part of that is just so much of businesses are still closed and there's only so much you can buy at Target or Amazon, but the other thing is deferred rent/mortgages might mean people are just saving the money they otherwise would have paid to their landlord/bank.
Its easy to make assumptions about possible to outcomes.
When people withhold money from the economy one possibility is deflation. People notice prices on desired items start to fall because nobody is buying new TVs, cars, furniture, etc. Demand does not start to pick up when prices are marked down to cost or below and sometimes not even then.
This is called deflation. More layoffs = less people buying things = even lower prices. Now you have a deflationary spiral leading to big layoffs, recession as businesses cut back to meet lowered demand. Lower GDP, less prosperity, etc.
Deflation was a big contributor to the Great Depression.
I dont know if we go into a deflationary spiral, but we might wind up with a Japanese style zombie economy. After the great expansions of 60s-70s and 80s, Japan hit a wall. China was on the rise, the population of Japan aged and the savings rate in hit all time highs. To discourage this, Japan cut rates to zero. The benefits were temporary. Theyve had zero rates for decades.
Personally I think its a good thing people are saving more. Having less than $500 saved is a recipe for trouble. You need at least 6 months of expenses saved. Sometimes thats hard to do when you live paycheck to paycheck. I blame landlords who have raised rents so high that the average family can no longer get ahead.