That's a very vague and circular statement as well though. There is no official definition for what counts as role playing in a game. Nobody has ever come up with one that didn't either exclude lots of classic RPGs, or include lots of games that nobody (even Diablo fans) would consider to be RPGs.
The circularity is impossible to bypass. RPGs are well defined. Role playing games existed before studios attempted to translate them on computers. The usual question emerged: you can try to bring role playing to video games or use broadly the label to qualify some types of video games, no matter how loosely they connect to the definition of role playing games.
It has been a work in progress as for every other genres. Even studios that wanted to bring role playing to video games had to start small, with small ambitions when it comes to role playing.
Constraints to bring role playing to video games are heavy and require a high load of developpment.
The elaboration of role play in video games could not start at the same level as non computer roleplay games. It had to start at a small level and through evolution and experience, role playing was expected to be built more and more.
But for this genre, instead of increasing, the dose of role playing has been decreased, with many studios even giving up on translating role playing to video games.
That is for path one.
It is also clear that some other studios decided to label RPGs games that are not connected to the definition of rpg that existed before trying to translate role playing on computers. Many games labelled RPGs are actually tactical skirmish wargames, as it exists elsewhere like table top/board games (that are not called RPGs)
From that moment, games that are not RPGs were labelled and introduce in the RPG category.
That is for path two.
The circularity is impossible to bypass from that observation. Since games whose goal was not role playing were labelled RPGs, anyone sticking to the general (non computer games) definition will exclude them. So up with the classic games exclusion argument.
And since games whose goal was not role playing were labelled RPGs, anyone using the "computer definition" will introduce games whose aim is not role playing.
The last point also leads to exclude the possibility that other genres can evolve and introduce new elements to meet gameplay demands.
Many players do not refer to the general definition but instead to a list of means that can used to enable role playing. There is a confusion between means and ends.
For example, if a system of character customization is included, it is RPG. But role playing can happen without a system of progression.
Same for story. Role playing does not need a story to happen.
So when other genres are expanded their gameplay and introduces these means to support games, they are also automatically shifted to RPG category.
In the end, as so many so called RPG elements are only means to support an end that other genres demand, you'll end with most games being a RPG, even though whose main focus is not role playing. This indeed destroys the "computer definition" as it catches so many games.
Return to the general definition is probably impossible as my belief is that actually players would not like playing role playing games on computers. That recalled, anyone sticking to the general definition of role playing games (no reason not to apply to video games) do not end with Diablo series being RPGs.