So did any philosopher/scholar ever criticized each other on the path they choose to attain Moksha.
I suppose many such examples can be found. I will give one example where Adi Shankara argues against the position that liberation can be achieved by a combination of jnAna (knowledge) and karma (action). He is most probably arguing against the position of the bhedAbheda school here, which believes in combining knowledge and actions for attaining moksha. He argues for the advaitic position that knowledge alone leads to liberation.
Shankara's Bhagavad Gita bhAshya 18.66
Since both Knowledge and action are thus enjoined as duties, therefore the doubt may arise that they, in combination as well, may become the cause of Liberation. Objection: What, again, would be the result of this inquiry? Vedantin: Well, the resut will verily be this: The ascertainment of one of these as the cause of the highest good. Hence this has to be investigated more extensively. Knowledge of the Self, however, is exclusively the cause of the highest good; for, through the removal of the idea of differences, it culminates in the result that is Liberation. The idea of distinction among action, agent and result is ever active with regard to the Self because of ignorance. This ignorance in the form, 'My work; I am the agent; I shall do this work for that resut', has been at work from time without beginning. The dispeller of this ignorance is this Knowledge regarding the Self-in the form, 'I am the absolute, non agent, free from action and result; there is none else other than myself because, when it (Knowledge) arises it despels the idea of differences which is the cause of engagement in action. The word 'however' above is used for ruling out the other two alternatives. This refutes the two other alternative views by showing that the highest good cannot be attained through mere actions, nor by a combination of Knowledge and action. Besides, since Liberation is not a product, therefore it is illogical that it should have action as its means. Indeed, an eternal entity cannot be produced by either action or Knowledge.
Objection: In that case, ever exclusive Knowledge is purposeless. Vedantin: No, since Knowledge, being the destroyer of ignorance, culminates in Liberation which is directly experienced result. The fact that Knowledge, which removes the darkness of ignorance, culminates in Liberation as its result is directly perceived in the same way as is the result of the light of a lamp which removes ignorance the form of sanke etc. and darkness from objects such as rope etc. Indeed, the result of light amounts to the mere (awareness of the) rope, free from the wrong notions of snake etc. So is the case with Knowledge. As in the case of the acts like 'cutting down', 'producing fire by friction' etc., in which accessories such as the agent and others operate, and which have perceivable results, there is no possiblity of (the agent etc.) engaging in any other activity giving some other result apart from 'splitting into two', 'seeing (or lighting of) fire' etc, similarly, in the case of the agent and the other factors engaged in the 'act' of steadfastness in Knowledge which has a tangible result, there is no possibility of (their) engagement in any other action which has a result different from that in the form of the sole existence of the Self. Hence, steadfastness in Knowledge combined with action is not logical.
Objection: May it not be argued that this is possible like the acts of eating and Agnihotra sacrifice etc.? [As such a common action as eating can go hand in hand with such Vedic rites as the Agnihotra-sacrifice, so, actions can be combined with Knowledge.] Vedantin: No, since it is unreasonable that, when Knowledge which resuts in Liberation is attained, there can remain a hankering for results of actions. Just as there is no desire for an action or its result [Action, i.e. digging etc.; result, i.e. bathing etc.] in connection with a well, pond, etc. when there is a flood all around, similarly when Knowledge which has Liberation for its result is attained there can be no possibility of hankering for any other result or any action which leads to it. Indeed, when somody is engaged in actions aimed at winning a kingdom, there can be no possibility of his engaging in any activity for securing a piece of land, or having a longing for it! Hence, action does not constitute the means to the highest good. Nor do Knowledge and action in combination. Further, Knowledge which has Liberation as its result can have no dependence on the assistance of action, because, being the remover of ignorance, it is opposed (to action). Verily, darkness cannot be the dispeller of darkness. Therefore Knowledge alone is the means to the highest good.
Only a portion of the bhAshya is posted here to illustrate the point. Reading the complete bhAshya would be more illuminating.
PS: Dont be in a hurry to accept this answer, even if you like it. It is worth waiting for other more comprehensive answers.