And how many of them will ever change it back?

For what its worth, there have been some suggestions in this subreddit, like...I'd say in beta, where folks suggested putting in an auto-squelch but it comes at a 'cost'. If you normally earned '10 xp' per match, reduce that 'gain' by 2 so you only earn '8'.

Essentially auto-squelch comes at the cost of faster progression, and costs you 2xp per match, but in Hearthstone XP only gets you 'golden basic cards' so it isn't truly that hampering. If you want to XP max, you'll keep it on when you feel like it.

Anyways....

I don't think proponents of auto-squelch have too much trouble with spamming emotes, it is just that well timed emote that comes after something disastrous that completely throws you off your game, and lingers. Some players like to play this like chess, focus 100% without distractions and give it their all.

It's also interesting how often people keep saying: "emotes are nothing you should be worked up about", "it's just a game", "it's a children's card game", "emotes annoy you? That's your problem. You need to STOP FEELING". As if humans came with this automatic dial that allowed them to 'stop emotion' at any time they wished.

How many people criticise sports fans for getting into a game, or how mental folks get when an opposing team scores? Or trash talk that happens between teams? Somehow video games are still seen as 'lesser' than sports even now, despite Hearthstone's thriving competitive scene.

People seem to vastly overestimate how many would use such a feature - if it is like you said, that it is only a vocal few that would like auto-squelch, then we clearly won't have a dearth of emotes in this game, and Blizzard should implement it. If there are more people actually getting annoyed by emotes, Blizzard SHOULD address it because majority of those players might not come back after getting 'burnt out' again and again (look elsewhere on Reddit other than this fan site - folks complain many times over how frustrating it is to play Hearthstone and to keep up).

This subreddit is willing to let scores of players burn out of Hearthstone just because they feel so attached to their 'emotes'.