It doesn't work where the results are already cornered by high reputation sites or loads of junk.

High reputation sites: travel, hotels, the popular marketplaces.

Junk: drugs, mattresses, pills to grow your hair back, cooking recipes, SEO.

An industry with very few competitors servicing professionals where services cost a lot, because in those situations

1. Everyone knows who the competitors are 2. You are either going to be paying for those services or not, and if you are you will decide which competitor you want to pay for based on something different than how they show up in your google.

Examples - Thomson Reuters' legal services, LexisNexis etc. I'm pretty sure the amount of times some lawyer searches for a term, ends up on some competing legal service and just says oh well I better just pay for this now is negligible.

Near or actual monopolies.

SEO in these cases might help rank, but you don't actually need to rank for your business.

Sure, do you have a specific type of industry in mind?

In my experience, it's brand new or still relatively young companies that SEO is often not great for. It might be a great thing to engage in in the future for them, but early stage companies strapped for resources need to be more focused on building out an actual brand rather than on ranking page 1 against competitors who may be spending 10-100x on marketing than them and have been around for years.

If you’re doing something completely new, there might not be too much organic traffic. E.g when AirBnB was launching, the users were not googling for ”home accommodation”, they were looking for hotels. Same for Twitter, nobody was looking for ”sms blogging platform”