Well I heard that chambering vs spammers is useful. Indeed it is, but not always. If you are unlucky, you will chamber him and since he is a spammer he can get very lucky and counterchamber you, which you did not expect since you thought he is a bad player.
If you hold your chamber you can kill him easily. Of course you can run the danger of overholding and of his spam hitting you.
As for exagerated holds it can be very annoying indeed. I do it sometimes too but merely because I am derping around, eventhough it does work sometimes. More annoying than that are the defensive players who simply block and then hold their stab. This makes chambering them extremely hard and your own holds are useless since the oponent does not intend on opening his block in order to chamber you. Spamming can be usefull here, but against a good defensive player, this too is useless. All you can do vs such a player is stay patient.
This is the most annoying oponent in my opinion and the oponent I lose to most. It might be effective but it is boring. Of course if you have just started playing and do not know chambers etc., this would be a good step for training your blocking. However, in my opinion everyone should try to learn as much as he can about all aspects of the melee system.
But since everyone or pretty much everyone has payed for this game, I wouldn't dream of telling people how to play their game. I still enjoy the melee and that is all that counts for me. I hope most people feel like that too, eventhough the melee is not perfect.