The problem with this sort of thing is that it require a lot of forethought and know how. The majority of criminals are stupid and reactionary.
Second, DNA evidence is not used in the majority of cases, and is usually not the only, or even the most compelling piece of evidence.
Lastly, in order to frame someone, you need a sample of their DNA from hair, etc. If you already have that, you can just plant that instead. Why go through the hassle of faking it when you have the real thing? While there probably are circumstances where blood is better than saliva or hair, it doesn’t make this a rational thing to do in most cases.