The person doing everything often becomes the reason nobody else learns.

The person who handles everything ends up as a bottleneck and, unintentionally, as the reason nobody else develops. Every time you step in because it is faster, someone else does not learn, and the dependence deepens until the arrangement cannot change without a crisis.

Pick one thing you always do and hand it over knowing it will be done worse for a while. The short-term cost is real. The alternative is that it stays yours permanently.