@Holo
In the near future you will be able to hide groups that you don't wish to appear.
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Linking to free official chapters has been a highly requested feature, so at least some people want this. Judging by the comments here and elsewhere, it would appear there is an overwhelming majority who do support this. Those of you who don't like it - wait for the ability to hide groups.
The ability to hide groups is really, badly needed. Or else a default option to stay in one group's releases for each manga. In this example, I refer you to the manga
Summertime Rendering. This managa has both MangaPlus's official releases and Ampas Scans releases upto Ch 15. If I read Ampas Scans from Ch 1 to Ch 15, I get automatically shunted to MangaPlus redirects at Ch 7.5 and 11.5 (because Ampas Scans has not released those chapters). This can be downright confusing, and is very disruptive to the reading experience.
In short, that ability to hide certain groups (or stay in one group's release for per manga) is very much needed. imho, a better alternative might be to move external links (to MangaPlus, or any other official releases) out of the reader completely. Just leave the external links in the manga title page, thereby reserving the manga reader for scanlation releases only.