Certified GKH Gardening Expert
Which article are you referring to? This article below says most almond trees are incompatible and need at least two varieties. It also says if you only have room for one tree, get a self-fertile variety and it lists three.
This article says there are a few self fertile varieties, but you are better off getting compatible combinations of cultivars.
I didn't see it in those articles, but similar articles mention that even though a tree is self-fertile, you will have a larger yield if you get more than one variety.