yes because i think it works out to be the same, basically?
let's say you have eth or usdc, if you cash out to an exchange then you have to CGT anyway
instead let's say you transfer crypto to your card wallet and convert it to usdc, that's a CGT event for the same amount, and then you're getting a CGT event when you buy something and it converts the USDC -> AUD/whatever currency you pay in but then you're only paying CGT on the gain (or getting a loss) on the currency spread
so it's very minimal, based on what price you acquired USDC at and what the conversation rate between USD<->AUD is at the time of purchase, and i think it basically evens out over time
there's approx 1-1.5% in fx and other fees when you spend, but you'd be hit with fx fees when you convert to aud anyway
those are the fees the cashback needs to overcome, and you can usually achieve that - ie tria has 6% up to $2k cap per month on their $250/yr card which works out to ~$100/month cashback (and then gravy on top of that if you get bonuses or perks to increase cashback percent or your cap)
other cards ie etherfi offer 3% cashback up to like 50k a month of spend or something
plus you can have your stables earning yield while they're in a lot of these protocols
basically it's an awesome way to hold and spend some of your crypto assets imo - the convenience is epic, even if it was breakeven i would still do it, but i think it's a net positive too
sorry for essay, new website coming soon that will explain this all a lot more clearly and make it easy to compare different cards/options