TCP Fast Open: expediting web services

If I am not mistaken, most modern TCP stacks do not hold data sent with a SYN, and do not send it either. For most applications, there would be relatively little advantage if they did. Requests usually fit in an MTU (or MSS) worth of data, and in the absence of something like TCP Fast Open, the target endpoint has to wait for an acknowledgement that can carry the full sub-MSS sized request without a problem. Where on the other hand, holding the data simply makes it easier to conduct SYN attacks.