Yes, there's the AMT trap for ISOs, but there's also an AMT credit that nobody ever seems to talk about, so net-net the AMT issue typically isn't as bad as some people make it out to be.
AMT credit is useful, but typically the issue is that 1. the taxpayer may not have savings to cover initial AMT and 2. the underlying security is volatile and could lose all value. If the security is just taxed a the time of sale, then the taxpayer definitely has the funds to pay (and the amount can be straight-up withheld) and no complex AMT schedules have to be filed.
AMT helps the government get paid sooner than later for fast-growing companies. This mechanism doesn't have to affect non-C-level execs to be effective.
