Because multiple people were comparing the Philippines to South Korea? E.g.,I’m trying to make sense why you are comparing the Philippines with South Korea and I concluded you were not talking about the 1980s as the OP stipulated.
South Korea next that gets you to the 1980s for Goldstar and Hyundai selling stuff in the USA
Even a corrupt dictator isn't the real problem, that didn't stop South Korea or Taiwan
For that matter, you brought up South Korea in your initial post:
South Korea[n per-capita GDP] was only twice as high as the Philippines while productivity was far higher.
Why would you do this if you weren't trying to compare South Korean and Filipino industrialization? If population wasn't an impediment to South Korea becoming a major industrial power, why is it suddenly a problem for the Philippines? This entirely stems from the fact that you're trying to argue that the population of the Philippines was somehow too small to allow it to become a major industrial power (which is all the OP actually asks for, the comment about China is only a proposed scenario) while at the same time ignoring the fact that there are multiple even smaller nations in the same region that are major industrial powers. Obviously the population is not actually an issue that will necessarily make them a "niche player" in any meaningful sense.
So bring this up. These are the real problems with industrializing the Philippines, not the number of people there.But as I pointed out their wages were not all that competitive. That of course isn’t the only reason. A big part of low cost manufacturing is clothing exports. The global market for cheap clothing was only so big and industrialists in South Korea moved faster than their Filipino competitors. Case in point, Philippines cotton production did not surpass South Korea 1961 levels until 1991 and then it crashed.
India's problem was the extreme regulation and difficulty of doing business there in the 1980s. If that hadn't been a problem, then they would indeed have had major advantages over China. As it was, China was rolling out the red carpet, which made up for the difficulty of doing business in Mandarin. It's also worth pointing out that India is not really that English-speaking. Only about 10% of India's population can speak English, according to an article I'm reading right now in Communications of the ACM on Indic-language computing, and only about 5% "is comfortable" reading or writing English. Meanwhile about 40 million Filipinos, or 40% of the population, are L2 English speakers (according to Wikipedia). That's a significant difference.As for English speaking being an advantage for manufacturing I don’t see evidence to support that. If that were true the Indian subcontinent would have an unbeatable advantage. English speaking Filipinos with a little education make much better income abroad and remittences are vital. One area the Philippines did well was call center work. But here they have to compete with cheaper Indian labor. But that’s OT since it’s not manufacturing.