Mahayana from its inception onwards has never been a singular movement; rather, it is a collection of movements that have adopted, more or less, some common overarching features, the primary one being the bodhisattva doctrine.
This collection of movements, which we can call the Mahayana, arose out of the “Buddha-ology” that developed after the death of the Buddha. As we see in the suttas, while the Buddha was alive he kept in check speculations about his nature, also keeping interest in him personally in check. Most, if not all of the Buddha’s recounting of his life in the suttas, are put in terms of what lead to his awakening.
After the Buddha’s death, no longer being there to keep things in check and in balance, considerable speculation arose as to who and what the Buddha was and how he became the Buddha. A lot of the various ideas floated are dealt with in the Kathavatthu, such as the docetic idea that the Buddha was a manifestation, a projection, of a being awakened eons before. This is an idea held by Mahayanists, and famously expounded very early on in the Lotus Sutra.
To a lesser or greater extent, all schools elevated the Buddha, focusing on his uniqueness. This, within the Mahayana, was pushed to an extreme, giving us a Buddha that exists forever as a saviour who supposedly frees all sentient beings. As the Buddha was aggrandized, deified within the Mahayana, the strong connexion between the Buddha, what it meant to be a Buddha, and the arahant as clearly outlined in the suttas was shattered.
The focus in the Mahayana became the Buddha and becoming a buddha. Bur even before the rise of the Mahayana, arising out of the post-mortem “Buddha-ology,” the basic features of the bodhistta path as a path of practice were developed by the various Mainstream Buddhist schools. Whereas in the Mainstream schools a bodhisatta practice was an option for those who were so inspired, it was not a doctrinal necessity for everyone.
Keeping that in mind:
"... even after its initial appearance in the public domain in the 2nd century [the Mahayana] appears to have remained an extremely limited minority movement - if it remained at all - that attracted absolutely no documented public or popular support for at least two more centuries. It is again a demonstrable fact that anything even approaching popular support for the Mahayana cannot be documented until 4th/5th century AD, and even then the support is overwhelmingly monastic, not lay, donors ... although there was - as we know from Chinese translations - a large and early Mahayana literature there was no early, organized, independent, publicly supported movement that it could have belonged to."
-- G. Schopen "The Inscription on the Ku.san image of Amitabha and the character of the early Mahayana in India." JIABS 10, 2 pgs 124-5
As a very small, essentially ignored by the Mainstream schools, movement, the Mahayana clearly developed as an oppositional movement. This is famously seen the dichotomy of the greater insights and compassion as found in the Mahayana versus the poor and at best temporary insights and attainments of the less able, less compassionate hinayana (a term of remarkable ugliness when applied to the teachings of the Buddha that is put into the mouth of the Buddha by the Mahayana).
The point is that much of its doctrinal thrust was oppositional and its doctrines crafted so that the Mahayana saw itself to be better than those of its perceived opponents. It is not that there are not genuine and useful critiques by the Mahayana of some aspects of the Mainstream schools, and it is not there are not useful insights developed by the Mahayana, but the unskillful, oppositional, and vituperative us-vs-themism nature of how it developed its doctrines seriously undercuts the nature of what it claims itself to be.
Now, as Ven Dhammanando has shown there is not a sustained critique of the Mahayana within the Theravada. That seems to be mostly the case across the board with the Mainstream schools who pretty ignored the Mahayana. Some comments here and there in their commentarial literature, but little sustained response to the Mahayana, while the Mahayana, as a minority movement trying to assert and distinguish itself, argued against the Mainstream schools, claiming of itself its superiority, and various factions within the Mahayana argued pointedly against each other, claiming superiority over each other.
While it has not happened yet, it would be quite possible for the Theravada, a Theravadin scholar or scholars, to mount a sustained critique of the Mahayana. It might be of interest, but I am not sure in the end it would be useful. It would likely add to the ongoing negativity that is already generated by the Mahayana’s unskillful us-vs-themism and not really change anything.
The Theravada clearly does not need the Mahayana, nor does it need the problems that the Mahayana has generated for itself by many of its doctrinal innovations that move far outside what the Buddha taught. What the Theravada offers is a full, complete path to practice that follows closely to the record we have of the historical Buddha’s teachings, and that is what is worth emphasizing.