I'm well aware that most hit songs start off as a basic acoustic guitar/piano track in some form but I'm not sure why you were raising that point or what it was adding to the discussion. Indeed, I may have been presumptuous about the smash hit point - but, in my defence, no one has disclosed their smash hit success for me to know/think otherwise. Kudos to such folk if they are quietly going about their forum business! I guess I should qualify the smash hit point by saying I meant that no one on here has broken into the UK Top 10 or the US Billboard in the same way and in the same time frame and with the same consistency as Max Martin, Taylor Swift, Ed Sheeran etc.... I literally mean a 'smash hit' like Baby One More Time, Shake it Off, Shape of You etc.
I don't buy the 'hit songs are only hits because of industry hacks' argument. Yes constant exposure and slick PR certainly helps and yes those backed by the millions of the industry are beneficiaries of this but ultimately n the final analysis the song has to be catchy/hooky/good enough to begin with. Whatever about how they are promoted and who they are promoted by/for, in substance they have to have that little something about them that will help them appeal to people. In many cases they are promoting a tried and tested product that they know will work. Listen to some acoustic covers of modern hits and you'll see even in their most stripped back form they have a commercial appeal. There was an interesting thread on here recently about being objective enough to evaluate one's own songs. Being completely frank and truthful can you say that when listening to the songs on Heart in work you really thought for even the slightest moment that your own songs were catchy/hooky/ as appealing as the ones you were listening to were? Could you genuinely imagine one of your songs coming on next and it feeling completely at home among the well polished, well written and well performed songs with proven commercial success that you were hearing?
IMHO Max Martin is more than just good at musical maths, he is incredibly talented. He wouldn't have cornered the pop market if he was simply a guy with a keyboard in one hand and a calculator in the other. It wasn't today or yesterday or last year or even 10 years ago that he was ripping it up - he's been at it since the Ace of Bass days. He's got a musical background so I'd hazard that his success is down to more than some chicanery with octaves... Again he's doing it with algorithms and with software that is available to people on this site - he isn't drinking the blood of anointed virgins or taking ground-up unicorn penis in his tea to give him the magical ability to write these songs! The key is, though, that he has a substantial degree of talent and has honed his craft meticulously over the years. That, plus an acute understanding of musical maths - that is REALLY knowing what works, what doesn't, when to stick to the rules, when to break the rules and how to do this in a way that 'clicks' - on a very gifted level, I'd submit, are the reasons why he has written a list of hits that far surpasses anything we are likely to accumulate between us times a thousand.
Also, why wouldn't it be legitimate to co-write with several people? You seem to infer Max Martin is somehow doing something wrong by writing with others and splitting credits. Modern technology has made collabing with many more people much easier. For instance, when MO and Major Lazer were writing 'Lean On' they were sending each other stems via the net from wherever MO was touring at the time. The current state of play is that many hits are written by songwriting TEAMS rather than a single team; literally, one team working on an intro hook, anther on the chorus, another on the verse etc. I don't think it matters if a song is written by 1 person or 100 people if it ends up appealing to people and tops the charts. It isn't wrong or devoid of talent to do what Max Martin and others do. In fact, it's a proven route to success...