"I don't need this" doesn't mean someone else doesn't.
I would agree that bookmarks, generally, are a poor fit to current needs or requirements. When a typical hard drive was, say, 100 - 500 MB, the idea of only saving the URL, and not the content, could be argued. With mobile devices having 128 GB - 1 TB of microSD storage, there's no reason you cannot store everything you've read, or at least everything you're interested in, locally, on desktop, laptop, or mobile.
Which is what you've done.
But you're running into the underlying problem (as am I): a pile of randomly-titled, poorly-metadata'd PDFs isn't particularly useful.
There are tools -- Zotero and ... some others -- which manage references, but IMO do so quite poorly. The problem is that what they introduce is a metadata vetting and management problem, and one that IMO GUI tools manage quite poorly. The fact that the tools aren't available on Mobile (I use an Android tablet almost exclusively, because reasons, and yes, it sucks in a great many ways), makes this problem all the more nontractable.
I have the same problem, it turns out, with bookreaders. I use two, mostly: PocketBook and FBReader, with ~2,000 or so references. Unfortunately, other than title and author search, I've little by way of organisation of these, which is ... a major problem.
I'm using Pocket, The Article Management Tool that Gets Worse The More You Use It[tm] (https://redd.it/5x2sfx), which ... suffers many of the same problems, and adds a few more of its own.