I am unimpressed by the authority of Merriam-Webster in this case, as this dictionary is descriptive rather then prescriptive. To fix the first use of a barbarism at a point 150 years ago simply means that some illiteracies are less vincible than others and that their imitation is persistent. Thus Fowler says of "orient" and "orientate": "The second, a long variant of the first, seems likely to prevail in the common figurative use." (2d ed., 1965, p. 423)