Searching within a topic

this idea came to me when doing one searches for knowledge and applies to big topics where long discussions are going on packed with usefull information.

What I run into is that with product launches, for example, there is enormous attention and often major topics arise around this product. Customers share their experiences, ask questions and the community is buzzing.

Where things become challenging is after a few pages where users start repeating the same questions, answers are lost in the bulk and the topic becomes too cumbersome to share knowledge and experiences. For example, this is one our biggest topics: KPN introduceert KPN TV+ 

And this is the 115 (!) page thread where I found all the info I needed in my quest for detailed info: Swedespeed forum

The result not being able to search is that often useful information cannot be found, for example to quote and help others. New topics will be created with already answered questions and information will be scattered.

My proposal is to allow users to search within topics themselves. To discover valuable information and give them the opportunity to respond to it. The community can stay on topic better and the quality of the content will improve with less moderation.

I'd love to here how your thougths are on this subject.