In the context of Russia, the company that made Telegram is headed by Pavel Durov, creator of the main Russian social network, vk.com. Don't know the exact history, but ultimately the social network ownership was transferred to a large IT corp, and Pavel Durov had some falling out with big wigs, and left Russia to create Telegram.

He is a kind of a rebellious figure in modern Russia, and, as younger generation generally dislikes the regime, he is viewed favorably, and a lot of Russians use Telegram because of that.

So blocking Telegram would be a "we're stronger than you" move by the government.