As someone who's always watched foreign movies (as in, not Portuguese, given my nationality) and now watches anime (in Japanese) with subtitles, I vehemently disagree with this. You're still watching the show: the subtitles only provide the translation of what's being said.
Your logic also carries the implication (at least to me) that one would have to learn a ton of languages to enjoy shows/films from different countries. Does this mean I should learn Japanese to watch anime? Or learn French to watch a French movie? I think it's possible to enjoy a show in the original language, provided with subtitles that represent a faithful translation of what's being said.
Do note that I'm not against dubs (unlike
@ManlySpirit), though I dislike dubs done for live-action films/shows given it becomes obvious that the people you see on the screen are not the same as you're hearing and it becomes odd as the lip movement doesn't match the sound. Dubs for animated works, I don't mind and find the idea of different actors from different countries doing their own take on a character interesting.
I've watched plenty of Disney movies dubbed in Portuguese as a kid, and with good voice acting that parents could enjoy, so I can't really speak against dubbed animated features. (Unless the acting is poorly done, of course.)
Ideally, it's best to provide with both options, which is a feasible option and people can have the freedom of choice. Like it dubbed? Watch it dubbed. Prefer hearing the original audio with subtitles? Watch it subbed.
Subbing vs. dubbing debates are quite pointless when there's the viable option of proving both and let the spectators choose.