So you’re saying that Gandhi accomplished nothing
Gandhi achieved a socio-economic mass mobilization. Boycotts, work stoppages, supply chain failures caused by mass mobilization. It wasn't just people parading through the streets. They inflicted real economic damage on the British Imperial State.
when millions followed him, they couldn’t just arrest them all
Thousands were killed by British-aligned police. Millions more were impoverished in retaliatory trade sanctions, embargoes, and other economic retaliations. The Indian state was set back decades by the English response to independence - not unlike how Cuba and Haiti have been deliberately impoverished in retaliation for bucking the American and French former overlords.
They could arrest Gandhi and Congress leaders all they wanted to, but the movement they inspired couldn’t be stopped.
The current Modi government is a stark reversal of policy from the Gandhian Indian socialist state. They've embraced a very western-oriented capitalist-friendly militant hierarchy that has fully rebutted the movement Gandhi lead. That is, in large part, through continuously aggravating tensions between caste cohorts and between Hindu and Muslim regional populations.
When millions follow you, and refuse to cooperate, the ruling class will suffer
Mobilizing and orienting millions of people requires a large, cohesive popular media campaign. Gandhi was able to tap into a huge underground of anti-British opposition. But even that wasn't able to overcome the base anti-Muslim sentiment that the Brits had fostered for centuries. Gandhi himself was the victim of this unfettered hatred, when he was assassinated at age 78 by an anti-Muslim fanatic during an interfaith prayer meeting in 1948.
Assassination of leading civil rights activists and organizers by hyper-partisan radicals has consistently worked dismantle national movements. From the slaying of US civil rights leaders in the 1960s to the bombings and assassinations of Latin American, African, and Pacific Island socialist organizers in the 70s, 80s, and 90s, we've seen the ruling class triumph through a persistent campaign of organized violence and stochastic terrorism.