Please elaborate advertised functionality for customers in Gutenberg requirements

Hi, I am a little confused about a requirement that theme forest provide. Please read this paragraph:
“Consider users who are not using Gutenberg and provide sensible fallbacks or alternatives wherever possible. Remember that any advertised functionality must be available to customers or your item may be disabled, so please be clear about any limitations.”.

Do i need to provide another builder like Elementor or Wpbakery? Waiting for the reply. Thanks

A sensible fallback in this case would be basic styling for the classic editor (for users who have installed the Classic Editor plugin). You do not need to provide another page builder.

If your theme supports earlier versions of WP (4.x) you will need to have full styling support for the Classic editor AND Gutenberg (if your theme is Gutenberg Optimized).

I hope this helps