[morrvs]

You bring up an interesting point. I intentionally used "may" in that statement as using .innerHTML can be both effective and performant enough (and a lot simpler).

A couple possible problems off the top of my head:

1. CSS transitions won't work if you re-render a complete chunk of HTML instead of toggling a class.

2. <a>, <button>, <input>, etc. may lose focus or even data on re-render (e.g. while filling out a form).

3. Text selection may be reset on re-render.

4. If you don't use event delegation, event listeners may need to be reattached.

I agree that for raw display .innerHTML may be sufficient, but it's surely not in general. That would make React almost irrelevant, by the way, which would be a huge surprise.