Tables are responsive in Drupal 8 views if you do the settings. You can eliminate some colums if the screen is narrow. In tables embedded in a text field they are not resposive, unless you add some CSS.
The Responsive Tables Filter sets tables responsive automatically.. It puts the content in one or 2 colums. It works in views as well as in the CKeditor tables. For the CKEditor you need to activate the setting.
See responsive tables filter.
The order is important...
A common table in the Text Editor. Normally not responsive without extra CSS.
Yep. Now it is.
An example in views.
Smartphone look (one item shown)