Thanks for sharing this!
Its true, there is no ethical way of gaining followers other than to use hashtags.
There are other methods such as following/unfollowing however they obviously do not like users who follow thousands each day (they will ban you), so how the hell are we to grow our accounts then!
I think they are wanting to (non-directly) force business to pay for IG advertising since they are unable to promote them self using any ethical way.
They can easily fix this problem if they chose to, however they are making a killing when selling advertising, so there is no motivation for them to fix it.