The problem is the ease and speed of creating such channels and adding huge numbers of subscribers easily. Therefore, it is better to modify the settings to prevent others from adding you to groups.
Also, the search option is bad for those who want to search for the official group.
I agree that using TG search bar is quite a bad idea, but I think there are quite some inexperienced users out there who stil uses the search function, thinking it'll be more accurate and focused than using a web search engine, while it is not necessarily true. Thus, embracing the spirit of better be safe than sorry, this thread --and other warning thread I made-- is an attempt to inform clueless members and newbies, which doubles as a report of a phising attempt.
It might be wise to add, another good idea --a better one than using google, actuallly-- is to get into the project's website or their official ANN thread. They most likely will have a link to their medias, like twitter, telegram, instagram, etc. which will --absolutely-- more accurate.