Please read your own note on Esacademy where you mention the problem of accidently modifying the boot vector. For which, earlier you needed a parallel programmer to correct, I do not know the situation now.
No, it not my or any other person's belief about RC reset, it is in their own datasheet for ISP programming, so obviously they got it wrong not us.
Apparently, Philips being late with concept of ISP rushed out with incomplete ISP.
Which is what puzzled a local programmer manufacturer, whether there is future in supporting Philips micros or not.