You have to realize that SCC is not quite the same as other FF hotel programs. The objective is not to collect points to get free nights and other items. SCC has always been a "service" club, offering special perks for IC's best and most frequent customers. While it is true that with more nights logged -- and dollars spent -- one moves up the elite chain, and benefits improve, but the basic perks of SCC are often better than other chain's elite award program perks.
Priority Club was started by Holiday Inn as a traditional FF hotel program. You stay and collect points which can be redeemed for free nights or gifts, or transferred to airline mileage accounts. Elite benefits are modest, and do improve from Gold to Platinum (or whatever), but they don't include many of the basics found in SCC aside from upgraded accommodation.
When Bass took over both chains, it brought its Priority Club to IC, but as a complement to the airline programs in which one could also earn miles for stays at IC hotels.
A few years ago, Hilton International, had a similar program, The Hilton Club. It offered the same perks to member HI patrons as SCC does. However, HI decided to shut down The Hilton Club when its commercial deal with Hilton USA brought it into HHonors. HI figured the elite benefits of Silver, Gold and Diamond -- and the Towers and elite floors -- would make up for the loss of The Hilton Club benefits. (I personally would like to see The Hilton Club operating today, but...)