Actually, they probably can't. At least, not if they're planning to pay their 92.5% in the event they miss out. You can't just spontaneously decide to draft someone who's asking for $800,000-$1million a season if he happens to be at your pick, because that would mean making space that is more than the 7.5% leeway you're allowed. You need to be confident you'll get him, and have a backup plan to get to 92.5% in case you don't. That would involve pushing back contract negotiations and other list management decisions, and is not the sort of thing you can do last minute. And you can't just backload the contract, because you'd need an equivalent value of other contracts front-loaded, which still requires significant planning in advance.
So yeah, to say every other team in the AFL can afford Tippett is bullshit. GWS remains the only risk, because with a bigger cap, their 7.5% is worth more, and they have the first pick, so if they want him they've got him. Other clubs are simply not in that position.