They can, to an extent, if you had lots time and a staffed lab. Crossbreeding yeast strains is kind of tough as most of the ones used in industrial fermentation (ie the stable, commonly used ones) don’t breed well with others and when they do crossbreed, the resulting new strain is often infertile itself. It’s possible, but difficult, unreliable and the resources required put it well beyond the scope of people who don’t own a brewing company.