"Thousands upon thousands of bookmarks is ridiculous and no one can convince me that they are ALL needed or even used on a semi-regular basis (by most people). I would venture to say that users who claim to have more than 5,000 bookmarks (and I've read several here making that claim) in all probability don't even have a working knowledge of what they have and whether or not many of those book-marked sites are even good anymore."
I have 25 bookmarks folders, with a varying ammount of bookmarks in them; about 2,500-3,000 bookmarks in total. Some are extremely old. Some don't work (I remove them when I find them), many still do. All the folders have different themes. Some I use daily. Some I use maybe once per month or once every 5-6 months even. The important thing is that they help me remember things, addresses to various pages that provide something that is important and/or useful and/or entertaining to me. Saying I shouldn't bookmark pages that catch my fancy and I may want to revisit in the future is obnoxious in the extreme. A bookmark isn't usaful only if you use it every day or every week. A bookmark is also useful for something you may want to revisit once per year, or even once every 2-3 years. The "goldfish memory" attitude of "well, if you don't use it every day, you should just not use it" is really annoying and silly.
I have a lot of books. Hundreds, possibly even thousands of them. Suggesting I throw away the ones I haven't read in the last few weeks isn't something most people would advocate. Yet, with bookmarks the same people have no qualms about saying "throw away anything you haven't used in a month". Do most people have goldfish memory and don't want to remember anything they don't visit regularly? Possibly. Are there people who want and need to store information longer? Yep. By making it so Opera is only usable by goldfish they alienate a significant portion of their potential userbase. Saying I should remove at least half of my bookmarks to use Opera is unhelpful. Saying I don't need them is being a complete asshole.