Until the middle of 2017, it wasn't possible to install any plugins on WordPress.com. If you used WordPress.com, you got a very stripped-down WordPress experience. However, that has started to change recently, and users on higher-level WordPress.com plans can now install their own plugins.
Last week, I was helping out a friend with a WordPress.com site and stumbled upon their WooCommerce store. I hadn't been into WordPress.com for some time, and was surprised by how different the experience was. I knew the "Posts" screen was different, but had no idea that WooCommerce also looks very different on WordPress.com.