You should really see how these people abuse bot votes at the eleventh hour:
Interestingly, their timezone is in South Asia around 3-7 am US time zone where, bidding competition for bots are lower. They used big bot votes such as @upme, @buildawhale @appreatiator with total $6-$10 or more SBD. They also reinvest earned SBD and withdraw some regularly. Easiest spamming business based on ROI in the world.
Please go through these users post including this https://steemit.com/@banglabhai.
Reason behind 3.5 days compliance rule is that when they used low level contents (e.g. mostly copy and paste Youtube videos) for bot voting, they will be prone to SBD fluctuation and flagging for plagiarism. This will reduce the abuse of rewardpool. Witnesseses and STINC are slow to react, therefore, some whales have to take action. Their actions are self-servicing. If they don't work for good purposes of STEEM, their investment will go down and they have the largest stake.
RE: Non-GumpyCompliant vote sellers are now to be used exclusively to profit from the reward pool!