The thing about HTML5 is that it does not enforce any real design patterns, so if you are not very careful with the design of your application, it will quickly become a horrible mess. I expect that is where the parent's disdain is coming from.
Interestingly, when you do introduce design patterns in your HTML5 app, it starts to very closely resemble a native application. At that point, there is little advantage to using HTML5 over native environments from a developer's perspective. The only real win from HTML5 being its ubiquity.
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The thing about HTML5 is that it does not enforce any real design patterns, so if you are not very careful with the design of your application, it will quickly become a horrible mess. I expect that is where the parent's disdain is coming from.
Interestingly, when you do introduce design patterns in your HTML5 app, it starts to very closely resemble a native application. At that point, there is little advantage to using HTML5 over native environments from a developer's perspective. The only real win from HTML5 being its ubiquity.