@marcelias Twitter added the RT feature after experiments showed that it increased the number of "tempests in a teapot" (so-called engagement) and increased viral behavior.
Mastodon is intentionally designed to add friction to the "viral" process and avoid tempests in a teapot. It works fabulously.
The lack of an RT function will not limit Mastodon's growth in any way.
@marcelias Ack! I just realized I typed RT in my comment when I meant "quote-tweet". QT then, I suppose. Lol.