Okay, as someone who does both self pubbing and trad, I'll put in my (longer) twopennies worth.
I won't go into the details of my sales - suffice to say I'm pretty happy with them based on this comparison (I have a tendency to compare myself to those selling mega-loads and be hard on myself, so that's a nice place to be.)
At the moment, for my first two books I have comparative sales figures for both and comparable income. Why? Because, unlike the person here, I did pay for editing for my sp work, so it took a little bit of time to break even whereas with the trad published book I was in pure profit right away, if you like, as I had no upfront work. I also have much more generous terms with my trad publisher.
In terms of work put into the titles - promotion, running kindle, supplying stores etc - my sp book does take a little more work. But only a little.
Having said that, I have a new book coming out next summer with a new publisher and I already have a lot less work to do on it - they are following up on promo for me, they're contacting people for blurbs, organising ARCs, review sites, arranging a launch (I didn't do one for Sunset yet as I have so little time to organise it, despite having a great venue) etc. I really have very little to do other than write it and push it on my existing platforms.
From now on, one of my first questions to any potential new publisher won't just be about percentage and money (I do, of course, make more per copy sp and my terms with my two publishers vary) but the crucial question - what will you do for me? (The same goes with short stories - I have several coming out this year and there is a vast difference between how each is being promoted/expectations on me/ support given. That is coming to matter as much as the money on offer.)
Here's the thing. I'm busy with writing now. I wasn't a year ago. I could churn out book after book and didn't see that each word is a precious thing. That there would come a time when it wasn't enough to be able to write and edit quickly because I had a long queue of words waiting for me to get to them. And, in the middle of that increased demand (there is one short story submission at least I don't think I will get to this year, and a couple of others I've had to say no to), I don't have the time to chase my own ARCs etc, and essentially be my pwn publisher.
So, that's what trad can give a writer (and, yes, you have to give up some of your potential income for it) - support to give you time to write. Because, to be successful, that's what you need to do.
@ralphkern talks about being his own brand and how I feel is along those lines but not quite the same. I am Jo Zebedee. No one else can write my books. But I'm also Joanne Zebedee, who has ran a consultancy under that name for years, and I am very aware that we must be professional when working in any role and not allow our personal quirks to undermine that professional work. It's not a brand, per se, but a pride in being who I am and a realisation that any mature writer has a Unique Selling Point (and I say mature simply because it takes a while to establish your own style and give people expectations of what they'll pick up and read, which may not be limited to genre - mine is close character work and a focus on personal and interpersonal conflict). It's up to me to protect that name and to build it.
Which means, essentially, I think the writer of the blog is right. Going with Tor grew their name further than self publishing did. Yes, the terms weren't great - and being agented might have helped, there, but more and more of us are operating quite happily without one and questioning the value of an agent in this age of open windows etc, so it might be a moot point (plus, of course, the terms would have had to be 15% higher) - but their name is what will sell future books and getting people to find that name and sample your USP is the single biggest challenge in the modern age of writing.