Well, it is "statpadding". How can I say this without taking anything away from Ronaldo though? Let me try.
With 13 goals in 6 games Ronaldo already surpasses Maradona's goal tally in the entire 84/85, the entire 86/87, the entire 88/89 and the entire 90/91 season with Napoli. Which automatically raises the question how much "13 in 6" is actually worth because you will have a hard time convincing many people that Ronaldo is a THAT much better goalscorer than Maradona, if at all. Consider this then. The Rayo Vallecano team Barcelona played against the past weekend has 17 new players in the squad. 9 on loan, the rest on a free transfer. They are the most extreme example but teams like Cordoba, Elche, Levante, Eibar etc. aren't any different. Then there are some teams like Athletic Bilbao which offer more quality but out of principle refuse to play defensive and push their backline 40 yards up in the Bernabeu. Just because. Meanwhile Real Madrid and Barcelona are splashing € 100M for Bale, € 90M-ish for Neymar (who knows the exact number anyway?), € 81M for Suarez, € 80M for James and so on. Illarramendi alone who is sitting on Madrid's bench is probably more expensive than the starting lineups of all La Liga teams except possibly Atletico Madrid, Valencia and Sevilla. But even with those I'm not so sure without looking it up. Atletico's wage bill is smaller than QPR's, was it? Consider also this. Once a team concedes 1 or 2 goals to Madrid/Barca, especially away from home, it usually becomes all about saving energy. Which produces 5, 6, 7 goal difference routs more often than not, unless Madrid/Barca also decide to call it a day and sub in youngstars. Some managers even rest their key players for those fixtures because they don't expect a win anyway in the Bernabeu/Camp Nou. Let's also not forget how much easier it is for the big teams to get penalty decisions compared to the small ones. THAT is the playing field in La Liga nowadays.
Not that it is much different in other leagues when it comes to the imbalance between modern super teams and regular teams (Bayern is another behemoth cannibalizing its own rivals). In La Liga the gap is just particularly big because Madrid and Barca have the whole package of history, prestige, present success, location and endless money which they don't hesitate to spend. Even the Champions League usually only starts getting interesting from the quarter finals onwards nowadays. Lots of teams to "statpad" against. How evenly matched is a game between Real Madrid and Ludogorez or Barca and APOEL Nikosia? By the time Benzema retires he too will break Raul's Champions League goalscoring record if he stays at Madrid. He's on 38 goals, only 8 goals shorts of Benfica's Eusebio, and he's only 26 years old.
I'm talking in historical context of course. All of this doesn't mean that it is easy and you can just replace Ronaldo/Messi with any other world class striker and they will pop up with similar numbers, especially over numerous seasons, or that these 2 can't score against proper teams. However those numbers and records also need to be seen in context.