The people complaining that Steam makes you contact them via email instead of over the phone, and then ranting about how Steam "must be a fraudulent company/is facilitating fraud", are providing the best example for why modern internet-based companies design their systems so that all service is done by email.
When people call up about things like credit card fraud, they are generally angry, and spend 95% of their time on the phone ranting and raving and abusing the poor sod working the phone lines. 5% of the time is spent actually providing relevant information so that the issue can be dealt with. No well-led company would permit this level of inefficiency, and no decent employer unnecessarily subjects their employees to the kind of abuse dished out by disgruntled callers. By directing service requests, including reporting fraud, to email, a worker can be many times more efficient and deal with issues much more quickly without having to also act as an untrained therapist to those who probably need one.
For those who have no idea what Steam is, raving on about them being corrupt or facilitating fraud - they're the largest video game retailer on the internet. They don't need or want the money from the basement-dwellers who are racking your credit card numbers, nor are they responsible for it. It's so easy to set up two-factor authentication for your credit and debit cards these days that if your card details get stolen and used it's most likely due to your own neglect of your card security - especially if you've been burned already and STILL neglect to set up security. I know being defrauded is upsetting, but take it out on the people defrauding you, not Steam. Its not their fault and as others have noted, they're actually quite good at dealing with it if you bother emailing them.
P.S. the card thieves likely aren't buying games or in-game purchases to play or use them. They can be resold on eBay, Amazon and other auction sites - it's probably one of the easier ways to turn stolen CC purchases into cash. If anyone is enabling this process, it's eBay and Amazon, not Steam.