Hi Peter,
My request is from the point of view of businesses and brands. They often have multiple people working their Twitter stream resulting a huge amount of tweets. A lot of these tweets are aimed at individuals and are less relevant to visitors of the website or blog. At the same time, you don’t want to filter out mentions and re-tweets entirely because they sometimes contain very valuable comments or testimonials.
Also consider organising tweets by topic. The same twitter account may be used for technical support, service status updates as well as promotions. When displaying tweets on the website it makes sense to show only those that are relevant to the page the visitor is viewing.
Last but not least, while the caching of tweets is a great feature, it also breaks a few business features Twitter offers, like the targeting of specific languages. (E.g. making sure our Chinese or German tweets don’t show up for English users.) The custom timelines would be a great work-around for this as well.
If you’re still not convinced, please also have a look at Twitter’s own examples of this feature: https://dev.twitter.com/blog/introducing-custom-timelines
Thanks for the reply!