I think vendor lock-in is at least as big a problem as searching and scaling. Arguably bigger for this audience: if I have easy unfettered access to the data itself I can always try something else for search/scale.

I've tried a few and at least twice tried to write my own (and gave up due to scope creep). Right now I just have a bunch of Markdown files and a giant messy DropBox folder and an almost-as-messy set of private GitHub repos. And photos. And videos. And e-mail. And backups. (What does one do with a Zip disk these days?)

I bet a lot of people my age (mid-40's) or older have the same problem: choosing or building a system we think would work long-term, and then gathering and organizing all the "legacy" stuff (which you definitely want!) is already an enormous undertaking, and so instead we live with a bunch of ad-hoc systems that aren't in any way cross-referenced.

Nobody wants to be the sysadmin of their own junk drawer, but I for one don't want years' worth of my stuff locked into somebody's Cloud du Jour.

(Then again, I have this same problem with actual paper documents, so maybe it's just me.)