There are a lot of people that like to collect the Silver Proof sets. And as sets not separated. That is a real downside to Silver Proofs. putting them in an Album is rather rediculous since in an Album you nor anyone could tell if Siver or regular. So the extra money spent would serve no purpose in an Album. And if you planned on selling such an Album, the purchaser would have to inspect each coin to see if really Silver and possibly get fingerprints or scratches on them. Putting each in a 2x2 or other size or type of flip again would serve no purpose. Again, difficult to tell if Silver or regular.
There are some things just better to be left as is.