Contemporary American English, particularly its colloquial variant, has a tendency to delete postpositions from verbs that have traditionally required them, e.g. cave for cave in, or bail for bail out. An example of this phenomenon that is constantly heard on the radio in the responses of interviewees is thanks for having me instead of the normative thanks for having me on, doubtless influenced by the confusion attendant upon the varied meanings (with and without postpositions) of the verb to have.
It is tempting to identify all such instances of truncated postpositions with a SEMANTIC ATTENUATION of the compound verb (in comparison with the untruncated standard variant), by which is meant a meaning that falls short of the full force of the untruncated verb form by remaining noncommittal as to the completion of the action. According to this analysis, for instance, thanks for having me is aspectually incomplete or noncommittal in comparison to thanks for having me on because the omission of the postposition comports a vagueness as to what specific semantic connotation of the verb have is at stake when it is conjoined with a postposition. This analysis is akin to the one I offered of the dropping of the reflexive after the verb commit as an attenuation of the complete degree of binding or pledging designated by commit myself/oneself/themselves, etc.