Many ideas people generate are a waste of time. This is because it seemed like a good idea but are not being checked upon. Instead, they keep going because of the initial momentum.

Larger companies can accommodate wasteful overheads, but startups won't be able to. If the organisation has capacity and resources, they often just hire more people instead of trimming the things that become irrelevant. That's why it's good to do a periodic irrelevance audit.