You sense correctly
If you were to talk with 100 independent mattress manufacturers who have their choice of any material they want to put in their mattresses … a large percentage of them tend to downplay memory foam and many won’t even make it … even though they have access to high quality memory foam and could easily include it in their designs.
There are several reasons for this … including some of the real reasons behind the new fire codes in the US which were more than anything IMO part of an effort to drive independents out of business because of the difficulties of prototyping a memory foam mattress (which to some degree has worked) but a bigger reason has to do with memory foam itself and its strengths and weaknesses and durability. These manufacturers are often multigenerational and depend on their local reputation more than anything else and many of them are not willing to risk their reputation on any type of memory foam. There is an article here which explores this in more detail.
Part of this as well is connected to the misinformation about memory foam and to the confusion and lack of understanding about memory foam in general in the consumer market.
Memory foam is only suitable for use in the upper layers of a mattress because by its nature … all memory foam is too soft to provide support for the body profile. It is a pressure relieving material that needs a firmer layer underneath it (usually polyfoam) to provide correct support. The support layers under the memory foam are also responsible for a big part of how a memory foam mattress feels.
In addition to this … there is a huge variety of different memory foams … some of which are really bad and only last a few months and some of which are much higher quality. Many consumers don’t realize that a “memory foam mattress” only means a few inches of memory foam over something else used for support. They also believe that “more is better” whereas in actual fact thinner layers of memory foam are actually much better. There should never be more memory foam in a mattress than is needed for an individuals pressure relief needs based on their height, weight, and sleeping positions.
I personally believe that latex … or even the highest quality polyfoam is a better material in many cases than memory foam but I also realize that some people like the unique memory foam feel. My personal favorite layering for memory foam is thinner layers mixed with either high quality polyfoam or latex foam in the comfort layers. This can help overcome some of the weaknesses of most memory foam such as its lack of breathability, it’s slower response, the difficulty of changing positions on it, and the heat issues that are connected to many memory foams. Latex is also far more durable than even the best memory foams (5 lbs and over made by a quality foam pourer), and low quality memory foams are among the least durable of all foams.
Because of the extreme amount of misinformation on the web about memory foam … many consumers believe that the cheap knockoffs that compare themselves to tempurpedic have some truth to them. While there are memory foams that are equal in quality to Tempur foam … most of the “junk” that is advertised and sold can’t compare to these higher quality foams.
So all in all … memory foam has its place in mattress manufacturing but it is not even close to the “panacaea” that many people believe it is. Many people have never compared memory foam to the pressure relieving abilities of higher quality materials such as low ILD latex which not only relieves pressure as well as memory foam but is far more supportive and durable so their feeling about memory foam is in a narrow frame of reference.