Beer kits: why/when would there be no need to cook the wort?

I made beer from malt extract a couple of times with satisfying results. I had been reading a lot about it upfront and practiced what I had learned. This meant ignoring the instructions that came with my malt extract kits though. I was convinced I needed to cook that stuff to get rid of substances that do not taste well. So I did each time. I also made sure to cool quickly using a self-made cooler.

Now what puzzles me is the instructions that come with the kit. These tell you to dissolve the extract in a bucket of warm water and just put the bucket away until it is time to bottle. No cooking, no avoiding temperatures over 30 degrees Celsius for an extended period of time.

Is this just a trade-off to make it as easy as possible, likely resulting in a sub-par beer or do these malt extract suppliers pre-process the stuff in such a way that there is indeed no added value in cooking?

I have been using the sirup kind of extract. There is also the solid grained type. I would like to know how each is produced and how, if this were the case, this removes the need to cook the wort.

There is another question asking about whether wort should be boiled or not here but this is different because I want to know more than a simple yes or no, I want to understand what the extract producers do to make boiling less of a necessity.