It is generally known that Modern Tamil (since around a century) totally simplified its alphabet from covering all Indic consonants to only consonants in Old Tamil (as written in Tolkāppiyam grammar using Vaṭṭeḻuttŭ, a descendant of Tamil-Brahmi).
Even Middle-Tamil had coverage for all Indic consonants, which evolved from Pallava script to the Grantha script.
So when exactly did this reform to remove non-South-Dravidian consonants from the Tamil script happen, thus standardizing the present day modern-Tamil script?
What is the reason and history behind that? (I heard it's mostly because of anti-IndoAryanism)
I found this line on Wiki:
The Tamil purist movement of the colonial era sought to purge the Grantha script from use and use the Tamil script exclusively. According to Kailasapathy, this was a part of Tamil nationalism and amounted to regional ethnic chauvinism.[13]
What does it mean to remove Grantha script and use only Tamil script? Isn't Tamil script already a descendant of the Pallava-Grantha script?
At a later period, Modern-Tamil standard seems to have allowed a few additional consonants {ஜ,ஷ,ஸ,ஹ} in its alphabet. When did this exactly happen? And what reason? Is it to reproduce sounds in texts like Bible?
And why are these called Grantha consonants? Isn't the entire Modern-Tamil alphabet a minimalist Grantha script?
Apologies for too many questions. I believe a proper brief on the history & politics of Tamil's linguistic-evolution would clarify all the above queries. If possible, kindly also provide references; it would be immensely helpful. Thanks!
Edit:
It looks like there were attempts to include the full Tamil-Grantha script into Tamil Unicode by the Indian government, but it seems to be not approved by Tamil Nadu government, calling Grantha as a script for Sanskrit.
Do they implicitly mean that Tamil script derived only from Pallava script, which is different from Pallava-Grantha script; the former having only Old-Tamil consonants and the latter having full Indic-coverage? If so, are there any references to show Pallava script only has the minimal-Tamil alphabet?