With the help of campaign managers, bitcointalk will be more active if they bring back the old way of accepting participants, like accepting even jr. member ranks. Most campaigns now only accept Hero to Legendary Members. I think Jr. Members rank is okay with the payment even if it is only $10 per week or less. This would also help the campaign and save some funds. But assume high amount of spam post once this once is implemented.
The truth is, due to the ICO boom, there were so many signature campaigns both that would pay in Bitcoin and altcoins (ICOs) thus so many opportunities. This gave an opportunity for even Jr Members to participating ICO signature campaigns, which were also so well rewarding most of the time in that Bull run.
After that period, the ICO bounties became less lucrative and people switched to Bitcoin paying signature campaigns. There was an influx of high ranking users and with the few campaigns left, Most CMs resorted to accepting only Sr Member ranks and above.