I went to block it and was suprised to find I can’t not see incest without going into the incest community to ‘block community.’

While going to the community and hitting the "block community" button is one way, its not the only way. For your desire to not enter the community, in the web browser, you can go into your settings and block from there:

Here's mine for example, go to your settings:

Select the Blocks tab:

You will find a "search" box there you can type in the Lemmy community name. Even a partial typing will return results and give you a list to choose from:

With this method you never have to enter the community to block it from your view.