I don't believe the thought ever was to use them in an MCO without augmentation. Attach a tank battalion to an SBCT to soak up the ATGM hits while the Strykers deploy infantry. Or dole out Stryker battalions to heavy units to augment their dismount capability.
Certainly they still have tactical mobility limits, but so do M1s. OTOH, they have theater and strategic mobility advantages over heavy units. An SBCT certainly isn't a speed bump in the same way as a light infantry unit. Each infantry squad has a Javelin at its disposal, IIRC. That's a lot of AT firepower.
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