I don’t follow what you’re arguing. It seems you’re agreeing - yes, Telegram could sell the login data.

The commenter you replied to was expressing a (snarky) hypothesis that Telegram will sell login data. You initially said this was nonsense, but are now saying that they could do so. That’s basically the point.

I'm just saying that implying that this feature would mean telegram start selling user data is nonsense. This is what the first comment was implying.

Ofc telegram can sell user data like any other company, and may be doing it for months for all we know.

Here you have the basic info (not ticking additional boxes) people share with the party your're logging into via Facebook login (for privacy reasons I have reset most fields):

{ PasswordExpirationDate: null, EmailVerified: false, IsActive: true, IsDeleted: false, Uid: null, CustomFields: null, IsEmailSubscribed: false, UserName: null, NoOfLogins: 3, ID: '', Provider: 'facebook', Prefix: null, FirstName: '', MiddleName: '', LastName: '', Suffix: null, FullName: '', NickName: null, ProfileName: '', BirthDate: '3/1/1985', Gender: 'M', Website: '', Email: null, Country: null, ThumbnailImageUrl: '', ImageUrl: '', Favicon: null, ProfileUrl: '', HomeTown: null, State: null, City: 'unknown', Industry: null, About: '', TimeZone: '3', LocalLanguage: 'en-US', CoverPhoto: null, TagLine: null, Language: 'en-US', Verified: 'true', UpdatedTime: '', Positions: null, Educations: null, PhoneNumbers: null, IMAccounts: null, Addresses: null, MainAddress: null, Created: null, LocalCity: null, ProfileCity: 'unknown', LocalCountry: 'France', ProfileCountry: null, FirstLogin: false, IsProtected: false, RelationshipStatus: '', Quota: '', Quote: '', InterestedIn: null, Interests: null, Religion: '', Political: '', Sports: null, InspirationalPeople: null, HttpsImageUrl: '', FollowersCount: 0, FriendsCount: 0, IsGeoEnabled: null, TotalStatusesCount: 0, Associations: null, NumRecommenders: 0, Honors: null, Awards: null, Skills: null, CurrentStatus: null, Certifications: null, Courses: null, Volunteer: null, RecommendationsReceived: null, Languages: null, Projects: null, Games: null, Family: null, TeleVisionShow: null, MutualFriends: null, Movies: null, Books: null, AgeRange: { Min: 21, Max: 0 }, PublicRepository: null, Hireable: false, RepositoryUrl: null, Age: '31', Patents: null, FavoriteThings: [], ProfessionalHeadline: null, ProviderAccessCredential: { AccessToken: '', TokenSecret: null }, RelatedProfileViews: null, KloutScore: null, LRUserID: null, PlacesLived: null, Publications: null, JobBookmarks: null, Suggestions: null, Badges: null, MemberUrlResources: null, TotalPrivateRepository: 0, Currency: 'EUR', StarredUrl: null, GistsUrl: null, PublicGists: 0, PrivateGists: 0, Subscription: null, Company: null, GravatarImageUrl: null, ProfileImageUrls: { Small: '', Square: '', Large: '', Profile: '' }, WebProfiles: null }