I think that there is a place for both of these foods in a healthy diet. I buy whole flax seeds and grind them in the blender before I use them so that the oil does not go rancid. Flax seeds also have a lot of good fiber, and since they have so much fiber, they can add fullness to foods without adding much of any carbohydrates.
I like to mix flax seeds and chia seeds (which are a good source of proteins as well as fiber), and you can use this as an ingredient when you are making keto bread and crackers, along with almond meal in place of regular white flour.
One of the things that most people miss on the keto diet is something that is similar to bread, which has way too many carbs to be practical on a low carb diet plan.
With the recipes that use ingredients like coconut flour, almond meal, flax and chia seeds, as well as psyllium, you can make good tasting substitutions for regular bread that are low enough in carbs to be used with a keto diet, and the flax and chia seeds also help make them much healthier than regular bread.