If you have been developing web apps 'for years', then you are probably used to thinking about database storage in terms of SQL.
When I first looked at Redis for example, my first impression was simply .. WTH ? Why so bare bones ?
My second thought was .. "Just look at the performance and scalability of this stuff - so it might be worth going old-skool on the database side of things just for the performance boost."
Yes - there is the performance and scalability angle, but that as it turns out is missing the point entirely.
One of the more difficult things to get your head around with this "new" way of working is getting over the fact that all of the sudden, the system requirements for database storage might be a LOT simpler than you are used to thinking.