In general I agree with your theory. Unity is important. But history is also equally important. You assume that Buddha came to cleanse Hinduism. But Buddhism was in India centuries before Brahminical religions spread to India (particularly South India). This conversion of South Indians from Buddhism and Jainism to Vaishnava and Shaiva religions and the introduction of systematic caste system was a severe blow to the south.

Most of the lower caste people today in Hinduism were mostly the followers of Buddhism and Jainism. Buddhist places of worship like the Puri, Tirupati, Palani and Sabarimala temples were converted to Hindu shrines. South Indian languages (particularly Tamil) were relegated to second level languages and preference was given to the Sanskrit language (please note that the earliest and best documentation of Indian history is Sangha period Tamil literature written by Buddhist and Jain monks). While every Indian today knows about Ramayana and Mahabharata how many Indians can name a single document from the over 400 Sangam period Tamil texts?

Buddha is not an avatar who came to cleanse Hinduism. Hinduism converted Buddhist followers of south India and then incorporated the Buddhist god to the Hindu pantheon. Before we talk about unity we should learn to be honest with each other.

I agree that the marginalization of Buddhism in India over the centuries is a great loss to India. But I would not go as far as saying that it is because of Hindu persecution and massacre. Buddhisms hold on India started waning at least 1200 years ago and there was no religion called Hinduism as we know it today. Also I believe that “Hinduism” did not eliminate the Buddhists but absorbed it (Lord Vishnu has very similar characteristics to Buddha (they almost look identical in some cases)). So what we call Hinduism today includes and is also greatly influenced by Buddhism.