Did Ambedkar think caste made India weaker as a nation?
Yes, and he made it the core of his case. His argument was that caste is not merely a division of labour but a division of labourers, ranked and sealed at birth, and that a society so divided cannot generate the common loyalty a nation runs on. People who may not dine together or marry across the line, he held, do not form one community; they form a collection of communities living side by side, and a collection is easy to rule and hard to defend.
He turned the usual nationalist reproach on its head. Where others said unity first and reform later, he answered that there was nothing to unite until the internal walls came down, and that a freedom won without dismantling them would simply transfer power from foreign rulers to a domestic upper caste. Swaraj, on his reading, was worth little to a man who could not draw water from the village well in his own free country.
This is why he treated social reform and national strength as the same project rather than rivals for attention. A nation, for him, was a psychological fact — a settled will to live together — and caste was engineered to prevent that will from forming. The disagreement with the mainstream freedom movement was not over whether to love India but over what would actually make it strong.
In the Journey: The speech that was never delivered, 1935–1936