The irony of long notice periods and immediate joining dates!

More and more candidates are unable to secure new jobs because of their long notice periods with the existing companies.

But should only the employers be blamed for this, or should candidates also share the blame? 

Let me be the devil's advocate here.

Why do employers look for immediate joinees?

1. They have an urgent position to fill.
2. More often than not, candidates with a long notice period use the offer letter as a bargaining tool to stay back or negotiate with another organisation. This puts companies in an awkward position when the candidate doesn't join.

Why a long notice period?

1. Organisations need time to find a trained joinee.
2. Fear of improper handovers.

What do you think, please do share your opinion?