A sport built on solitude
For most of tennis's modern history, competitors were expected to solve every problem in a match without direct guidance once play began, reflecting an idea that the sport was testing a single player's judgement as much as their shots. This is unusual among major sports, most of which allow constant tactical input from a sideline, and it shaped how players trained: reading an opponent and adjusting a game plan in real time was treated as a core skill rather than something a coach could simply supply from the stands.
A rule that was hard to police
In practice the ban was difficult to enforce, since a coach can convey a great deal through posture, a signal or a shouted phrase that sounds like encouragement but carries a specific tactical meaning. Umpires rarely wanted to adjudicate ambiguous gestures from a box seat many metres away, and the rule was applied unevenly across tournaments, which created a long-running credibility problem for a regulation that everyone knew existed but few believed was consistently enforced.
Where the rules stand now
Several tournaments have since introduced limited, explicit coaching windows rather than pretending the old ban was watertight, allowing brief exchanges at set breaks or via approved signals under supervision. This has not ended the debate about whether coaching belongs in tennis at all, but it has replaced an unenforceable blanket rule with a narrower one that at least matches what was already happening, and viewers can now expect the practice to vary by tournament rather than assume a single universal standard.