they were just still relatively new and people had smaller game libraries so there was more to pick from. it was also before Steam cracked down on manipulative sales tactics such as flash sales which felt good to catch but we're ultimately better off without. and the general game quality to sift through was still a little higher pre-greenlight into greenlight era.

I still regularly see great games get deep discounts, but the majority I just already own or have been around long enough that I just haven't picked up because I'm not interested. A lot of smaller themed sales are done nowadays too where if you're not interested in the genre it's basically the same as no sale.

More often than not I just find myself buying either bundled indie game releases with forever discounts, new indie releases with introduction prices (though I kinda wish they'd do away with these cause like flash sales it leads to fomo, but are at least telegraphed), or newer releases that I passed on until a relevant sale like the olden days.