This is how I assumed it worked tbh, that any members you gain at 70% would be a loss financially, and permanently, since they will also be classed as having joined at that rate, but a benefit as far as numbers go. The 70% to me is for people with fewer members who want to increase them more quickly, so they are a loss financially but a gain numbers wise, with the theory that if you gain more members from this, then switch it off, more people will see the now higher number of members and be more likely to want to join them, and will then join at the lower percentage rate. It's just a shortcut to me, assuming it works, for people who think doing this will get them more members faster than doing it themselves. If I see two almost identical groups, which there are quite a lot of on here (I found 8 with identical names the other day), then the group with the higher number of members makes me think, correctly or otherwise, that that group must be "better", because more people have already made the choice I'm now making and joined it before me. So switching to 70% temporarily is a way to get that higher number faster (assuming it works) which would then result in a long term benefit more of perception, than financially. But eventually financially, if more people join later as a result.