How often is "we need more candidates" actually the wrong diagnosis?

I've noticed something interesting when talking to recruitment agencies.

A client says:

We need more candidates

So the agency starts sourcing harder, spends more on job ads, reaches out to more people...

But sometimes the vacancy still doesn't get filled.

When you dig deeper, the bottleneck wasn't candidate volume at all.

It was something like:

- Slow hiring decisions causing candidates to accept other offers.

- Salaries that weren't competitive for the market.

- A hiring process with too many interview stages.

- A job description attracting the wrong people.

- Hiring managers rejecting qualified candidates because they're looking for a "perfect" fit.

In those situations, more candidates don't solve the problem. They just create more work.

I'm curious how other agency owners see this.

How often do you find that the client's stated problem isn't the real problem?

What's the biggest "hidden bottleneck" you've seen that clients completely missed?