The idea was that by including such violent-adjacent (but not directly violent) people into the political mainstream, they would be over time deradicalized even if they might praise violence abstractly, they would eventually become invested in the political process and participate.
Many of the articles discussing this talked about how socialist movements of the early 20th century often started out radical but then became centrist.
On the other hand, cracking down on the violent-adjacent would just further radicalize them and push them into the violent underground.
The debate became something of a moot point eventually, in the 90's it looked like democracy advocates in many Middle Eastern countries would gradually gain power and would need to make decisions about whether or not to crack down, of course that did not happen (except in Tunisia, where I think this debate still has some significance).
Anyways the current discussions about whether or not to "deplatform" the far-right remind me a little of these debates in the 90's. Of course, deciding whether or not to "deplatform" is very different than deciding whether or not to round-up and jail everyone, and so the parallels are strictly limited.