AD 900: the Kavi script is alive and well on Manila.
AD 1300: Someone etches a Philippine script on a pot. I've got an image of it here, characters handily numbered.
It's similar to Baybayin, kudlits and all. Could easily be a parent script.
AD 1500: Baybayin was in use by the general population.
By the end of the 1600s Baybayin is moribund.
A few small and remote populations continue to write, including Tagbanwa, Buhid, Hanunóo, and Kapampangan: more or less versions of Baybayin. Tagbanwa, Hanunóo and Buhid appear to have evolved along similar lines, while Kapampangan uses fewer characters, but retains Kawi word construction rules. In many respects, Kapampangan seems to be midway between Kavi and Baybayin.
And some Filipino native writing has survived to the present day.
But between Tagalog and Ilocano speakers there are 65+ million people, versus perhaps 3 million using Kapampangan, and a few tens of thousands of people using the other surviving abugidas.
And so we come to the modernization problem: how best the Baybayin can speak in modern Tagalog and Ilocano.
I begin to understand. It's not a matter of stamping out the surviving scripts; it's a matter of re-establishing a script for Tagalog and Ilocano. And the place to start is with "classical" Baybayin.
Fortunately, the Filipino script was a continuum of writing styles and methods using similar characters. Different areas, and even perhaps different individuals, approached the problem in different ways, but fundamentally with the same character set.
This is not a place for invention, but rather, accommodation and patience, perhaps.