Couple of things on this. First the debate isn't about tiered PB; it's about an independent "microaward" for good performances alongside PB. Secondly it's not about introducing something tomorrow but starting a discussion about the changes required to make FI mainstream. https://twitter.com/FiPiglet/status/1333823580119965701
The current PB system simply does not produce enough winners on days/weekends with lots of games. This depresses the market and reduces excitement unless you have someone in the PB race.
It would be possible to buy a port of ten great well known footballers who are in form and win no PB for months. As any psychologist will tell you this is not a recipe for customer retention.
At the same time the current reward system has been bolted together in pieces over multiple announcements. There are 4 ways to win; multiple different deadlines; and quirks like the multiplier. It's a significant barrier to entry for new customers.
So my view is that FI should, carefully and not for immediate introduction, start working on a comprehensive refresh designed to make the product more attractive.
I'm not suggesting an exact system because I don't have the data to model it but the principles of more regular wins and a simpler, coherent, system seem inarguable to me.