If economists believe it, it must be true:).

More seriously though, it's not as simple as 25% fewer jobs, or an economy that grows 25%. For example the number of elected positions is pretty fixed, and all those octogenarians in the senate are certainly blocking younger talent.

Politics may be an extreme example, but lots of other jobs are "proportional". There's a fixed number of plumbing jobs (per million head of population) so adding 25% more plumbers dilutes the plumbing pool. A boon in construction would drive up the demand for plumbers, but construction booms come and go.

The "economy" is (again simplistically) a measure of money flow. It doesn't really measure "production" as much as it measures "cash velocity". As such having a retired tranche spending all day long is a good thing.

And yes, more labor would lead to a growing economy. But a lot of that growth is in "poor quality" jobs (aka service level jobs) not "new production".

In other words the economy "grows" if money changes hands quickly. The standard of living though is more tied to "production".

Take, for example, health care. The sector can grow 25% by adding more admin staff, claims evaluators etc. None of which results in better health outcomes. Or it can grow by building hospitals, training doctors and nurses. Both increase the economy, both offer more jobs, but only one leads to a higher standard of health.

In truth the current economy is built around the customers free time. From music, movies and tv, to sports, travel, phones, social media, online advertising and sales, deliveries (of goods or people), restaurants (fast or slow), home improvement, it's all about monetizing free time.

Having a large customer base with nothing but free time is what makes it all work.