Engine oils like anything else, do get reformulated to address new issues as they "turn up", this new API approval which is SP, I think, has been available for maybe a few years to address the
problem known as LSPI which can occur when typically small modern Turbo charged direct injection petrol engine ingest engine oil in their in coming air, that will be happening for many of these engines and going unnoticed but is not really something that is desirable, any oils meeting this later SP approval will be more resistant to supporting LSPI which for me, can only be a good thing.
So, yes this latest reformulation of Mobil 1 ESP 5W-30 should be better than the previous one which I think was SL, but that does not make the oils still at SL etc approval terrible, it is just an aspect of some newer engine oils that I had read was being addressed, I am a long term user of Mobil 1 ESP 5W-30, and my wife's 2015 VW Polo 1.2TSI 110PS, is a small turbo charged direct injection petrol engine, so finding that Mobil had addressed this issue, suited me. I don't know why many other engine oil brands are either being a bit shy about which API approval they are meeting/exceeding though, I'd think that VW Group will be burying this "improvement" inside some of their very latest approval ratings/spec and not making a noise about it. Maybe a lot like Apple's frequent S/W updates to "improve" your user experience, ie nothing wrong in the first place, we're just making it better.