2) Crooters are afraid that if they tell you the company name in their initial contact email, you will attempt to snipe them by applying for the job yourself without their help. Once they have you on the horn, they can instruct you to only deal with the company through them. Most (especially young) developers will be good little do-bees and do just that.
> Why is it always some mumbling about “growth opportunities” and how I’m a “good match” and so on?
3) You think a crooter actually reads your résumé? Bahahahahaha... Oh, you sweet summer child. Crooters only ever come across your résumé. Translation: Their ATS snarfed it up while crawling the big tech job sites (Indeed, Dice, LinkedIn, etc.) and returned your name when they did a keyword search. When the crooter says "I think you might be a good fit for the role" that's all it means -- your name came up when they plugged keywords in for that role.
As others have pointed out, it's spam-o-nomics: do this enough times, and eventually there'll be a candidate who'll bite, be a match, and go on to work for the client netting a sweet fat commission for the crooter. All they have to do is keep farming the system.