I wasn't the ref, but even if I was I'd not have done much different. No one benefits from a caution.
"No one benefits from a caution" – I have to disagree.
You mention that subbing a player off is educational. I completely disagree. This approach, often seen in Academy football, misses the point. Being subbed off isn’t a real consequence, and most coaches wouldn’t hesitate to bring a player back on if it meant a better chance of winning.
As a player, I quickly learned what was acceptable and what wasn’t after receiving my first caution. For what it’s worth, I was once subbed off in a youth friendly for a tackle deemed "too strong." My reaction? Annoyance and frustration, because I believed the tackle was perfectly fair. Had I been booked in that situation, I might have understood the issue more clearly.
The phrasing you use—“appalling tackles”—sounds like it crosses the line from reckless into dangerous territory, possibly deserving a red card. As referees, we are paid to enforce the LOTG, not to do favours for players, teams, or coaches. Subbing a player off instead of issuing a caution can create inconsistency, leading to the infamous “last week’s ref” comparison.
To clarify, I’m not advocating for sending off 7 year olds, which ties back to my opening point: I don’t believe games at that level need qualified referees. However, as far as I am concerned, from U12 and up, players should be held accountable under the LOTG.