For a successful operator, the cost of splitting a pool is almost zero. This is because the required pledge is 0. Matters get worse because the min fix cost (i.e. 340 ADA) is well, fixed. It does not take the change of ADA price into account. Running decent hardware with N hours high skilled work may cost a fix amount of $ but not a fix amount of ADA. In short, the fix cost should be more flexible IMHO.
Also, a pool gets saturated at a certain max stake, but not as a function of the owner’s pledge. Some large pools have ridiculously little skin in the game (perhaps due to their splitting). Rewards could diminish when pledge drops below 3% of the pools active stake (e.g). This would be akin some sort of “healthy band” between min pledge max active stake.
Perhaps this is what a0 is about, when it gets implemented. In any case, because “Pool operators that run multiple pools with small pledge hurt delegators and smaller operators”, should IMHO discouraged more effectively let alone be endorsed by Daedalus ranking.