I agree. We (Christians) do often read this passage as contrasting believers with unbelievers, but that is projecting our modern context into the ancient text. We have to remember Jesus’ audience when he said “to you it has been given…” He was speaking to his inner circle, and the contrast he was drawing was not between his followers and Gentile unbelievers, but between his disciples and their fellow Jews, who also read the scriptures. This is similar to other statements Jesus made, such as:
“You study the scriptures thoroughly because you think in them you possess eternal life, and it is these same scriptures that testify about me, but you are not willing to come to me so that you may have life.”
Or, to hit even closer to home: “If they do not respond to Moses and the prophets, they will not be convinced even if someone rises from the dead”
It is the intended meaning. Isaiah and Ezekiel use it the same way. If you and @Mervin_Bitikofer will forgive me for quoting instead of paraphrasing in my own words, here is how G.K. Beale explained it in his essay The Purpose of Symbolism in the Book of Revelation:
When did the prophets primarily use symbolism? The prophets living toward the end of Israel’s history had the primary role of warning Israel to repent, or they soon would be judged (Isaiah, Jeremiah, Ezekiel, Zechariah, Daniel). … At first, they delivered their warnings in a very rational and sermonic manner, convicting their audience of sin and self-serving moral permissiveness, and recalling for them lessons from their own history. However, the prophets had little positive effect because of their audience’s spiritual anesthesia. They had become anesthetized because of their habitual avoidance toward changing their comfortable, sinful lifestyle. Their hearts had become hardened to rational, historical, and sermonic warning methods (Isaiah 6; Ezekiel 17). Therefore, the prophets took up forms of warning that might gain them a better hearing or better attention—they used symbolic action, parables, and words (Isa. 7:3; 8:1, 3-4; Ezek. 12:3-16, 22-23; 15:1-8; 17:1-24). Such a change in their form of warning was effective only with the faithful remnant. With those who “have ears to hear and hear not” (Isa. 6:9-10) and have become hard hearted, symbolic language and parables cause them to misunderstand further. When the prophets used symbolic parables, it was a sign that judgment was in the process of coming upon Israel (i.e., the Babylonian exile). Therefore, for hardened unbelievers (Israel), the literary form of symbolic parable (mashal) appears whenever ordinary warnings are no longer heeded, and no warning will ever be heeded by those so far disobeying, but the believing remnant can be shocked, by the unusual parables, back into the reality of their faith. This is the point of Isaiah 6:9-10, where the prophet is commissioned to tell Israel to “keep on listening but do not perceive . . . render the hearts of this people insensitive, their ears dull . . . lest they . . . hear with their ears . . . and repent and be healed.”
The parables are also intended to have a jolting effect on the remnant who have become complacent among the compromising majority. Israel did not want to hear the truth, and when it was presented straightforwardly to convict them of sin, they would not accept the fact of their sin. The parables, however, functioned to awake those among the true, righteous remnant from their sinful sleep. The same pattern found in Isaiah is apparent in Ezekiel, where the Isaianic hearing language occurs in Ezekiel 3:27 (“he who hears, let him hear”), followed directly by the prophet’s first parable, and in 12:2 (“they have ears to hear, but they do not hear”), followed immediately in verses 3-16 by the prophet’s first parabolic act before onlooking Israel (for similar wording to Ezekiel’s hearing formulae cf. Jer. 5:21; 17:23). Ezekiel’s usage is a development of that already found in Isaiah. Thus, the parables of the prophets served to judge intractably unrepentant people but shock the faithful remnant out of their spiritually numb and lethargic condition.