Who said that before Rambam's 13 principles it was allowed to have different opinions about the Messiah?

Question

I don't exactly remember the name of the rabbi who said this (Not sure if it was Chasam Sofer?) and I don't exactly remember what he said but from what I understood and remember was that before Rambam codified the 13 principles, which included the belief in the future coming of the Messiah, there could be differing opinions regarding the role and nature of the messiah. I also think the rabbi or the writer of the article gave an example that in the Talmud there were opinions such as that there will not even be a literal human messiah but God will directly intervene.

However, once Rambam codified the 13 principles it became forbidden to hold contradictory opinions like that. I also read about something similar regarding the nature of God in another article. That before Rambam also codified the 13 principles it was allowed for people to have different opinions about the nature of God. That is why the Talmud has many discussions representing God in a corporeal body. And just as with the messiah, once Rambam codified the 13 principles those opinions became forbidden to accept about the nature of God.

Answer 1

The Chasam Sofer indeed said this, in his last responsum on Yoreh Deiah (# 356):

והאומר אין משיח וקים לי' כרבי הלל הרי הוא כופר בכלל התורה דכיילי אחרי רבים להטות כיון שרבו עליו חכמי ישראל ואמרו דלא כוותי' שוב אין אדם ראוי' להמשך אחריו

And one who says "there is no Messiah for Israel" and holds like Rabbi Hillel is a denier of the Torah because we measure by the majority. Since the Sages of Israel amassed against him and they said not like him, henceforth it is improper for anyone to follow after him.

Rabbi Hillel's view is found in Sanhedrin 99a:

ר' הילל אומר אין להם משיח לישראל שכבר אכלוהו בימי חזקיה אמר רב יוסף שרא ליה מריה לרבי הילל חזקיה אימת הוה בבית ראשון ואילו זכריה קא מתנבי בבית שני ואמר גילי מאד בת ציון הריעי בת ירושלים הנה מלכך יבא לך צדיק ונושע הוא עני ורוכב על חמור ועל עיר בן אתונות

R. Hillel said: There shall be no Messiah for Israel, because they have already enjoyed him in the days of Hezekiah. R. Joseph said: May God forgive him [for saying so]. Now, when did Hezekiah flourish? During the first Temple. Yet Zechariah, prophesying in the days of the second, proclaimed, Rejoice greatly, O daughter of Zion, shout, O daughter of Jerusalem, behold, thy king cometh unto thee! he is just, and having salvation, lowly, and riding upon an ass, and upon a colt the foal of an ass. (Soncino translation)

Note that this does not appear to be the consensus of rishonim on how to deal with Rabbi Hillel's opinion. In fact several rishonim use this as a proof that Rambam is incorrect that belief in the Messiah is a fundamental belief.

For instance, R. Joseph Albo writes the following:

Sefer HaIkkarim 1:1

אלא שבלי ספק רבי הלל לא היה מאמין בביאת המשיח כלל ואף על פי כן לא היה נמנה בכלל הכופרים לפי שאין ביאת המשיח עקר לתורת משה כמו שכתב הרמב"ם ז"ל כי כבר יצוייר מציאותה זולתו

Rather, without a doubt Rabbi Hillel did not believe in the coming of the Messiah at all, and even so he was not counted among the deniers because the coming of the Messiah is not fundamental to the Torah of Moses like Rambam of blessed memory wrote since it's [Judaism's] existence is already conceivable without it [the Messiah].

Similarly, R. Isaiah (the Younger) of Trani writes the following:

Riaz Kuntres HaRayos Sanhedrin 90a

שהרי הלל שהיה מחכמי התלמוד היה אומר אין משיח לישראל שכבר אכלוהו בימי חזקיהו וכל המקראות שנאמרו על הגואל היה מפרשן לשעבר ולא נקרא כופר בכך

For behold Hillel – who was of the Sages of the Talmud – would say "there is no Messiah for Israel because they already consumed it in the days of Hezekiah", and all the verses that were said about the redeemer he would explain [as referring] to that which has passed, and [yet] he was not called a denier for this.