We should remember that the retweet feature was originally created by the community, like, years before twitter implemented it officially. You'll compose a tweet with the format "RT @username <quote post>" and broadcast it to all your followers. There's no reason mastodon users can't do the same. Right?
Slightly off-topic but important mention about the RT feature. RT was definitely not the first "feature" and there were many other ones which existed. There were some factors that led to the adoption of the RT convention [0].
> The inventors of these variations were not the typical user. They posted more tweets, had higher network degree, and were more likely to describe themselves with words like “geek” and “founder”; in other words, they were the core members of the Twitter community. The early adopters were also more active and innovative. The variations spread through densely connected networks, bouncing from person to person in a way that meant most adopters of the varia- tion were fewer than two hops from someone who had never been exposed to the variation on Twitter when they first used it. This could be a general finding, that social conventions are more likely to arise in the active and densely connected parts of a community.