To make it shorter to hold a cap more then the enemy team for 167 seconds matches the 500 points gotten by killing 20 more tanks in a whole match.
If a match lasts 10 minutes, so 600 seconds it means that holding a cap more for a little more then 25% of the time is as effective as killing 20 more tanks, and also, as some players act in a very selfish way, caring more of their personal result, farming damage and kills, to cap is very rewarding for the player that does it. So often i see that the one that did the most damage and kills does not rank very high as other players with less damage was well rewarded by capping.
And I believe that it is a very important thing to understand, that some players completely miss, not only no cap no win is true but also no cap no good personal result as usually who gets the gold medal in a won match is the one that did damage and kills, but also cared about capping, while i see often in the loosing time the iron medal having a lot of damage and kills but no points for capping.
To focus on kills and damage is not wrong, but only if you do that to allow some other friendly tank to win the battle for a cap, a sniper that kills the enemy low health tanks and soften the high health ones while your front liners are brawling against enemy tanks to win a cap is as useful as the MBT that actually caps after winning the brawling, while a sniper that focuses on other not important points of the map, maybe killing some tank that is not doing anything to help his team to cap and win is not so useful for the party.
Not all tanks are designed to cap, you need some armor or very good mobility to do it, but all the tanks can in their own way give their contribution to win the caps.