The chapter recounts Jesus' conversation with the Pharisees who were seeking to entangle him with arguments at law, verse 15:
I say this because immediately following this engagement with the Pharisees, Jesus turns to the multitudes and His disciples in chapter 23 and says this:
But all their works they do for to be seen of men: they make broad their phylacteries, and enlarge the borders of their garments, And love the uppermost rooms at feasts, and the chief seats in the synagogues, And greetings in the markets, and to be called of men, Rabbi, Rabbi.
But be not ye called Rabbi: for one is your Master, [even] Christ; and all ye are brethren. And call no [man] your father upon the earth: for one is your Father, which is in heaven. Neither be ye called masters: for one is your Master, [even] Christ.
But he that is greatest among you shall be your servant. And whosoever shall exalt himself shall be abased; and he that shall humble himself shall be exalted.
BTW, the failure to love is so serious an offense - it is Jesus' first indictment of the church. In Revelation 2, speaking to the church of Ephesus:
"All the law is fulfilled in one word, and that is, love. See Rom. 13:10. All obedience begins in the affections, and nothing in religion is done right, that is not done there first. Love is the leading affection, which gives law, and gives ground, to the rest; and therefore that, as the main fort, is to be first secured and garrisoned for God. Man is a creature cut out for love; thus therefore is the law written in the heart, that it is a law of love. Love is a short and sweet word; and, if that be the fulfilling of the law, surely the yoke of the command is very easy. Love is the rest and satisfaction of the soul; if we walk in this good old way, we shall find rest."
The sum of the Law is indeed Love
Again, you miss Jesus point. He gives 2 commandments as an answer to the question "Which is the greatest commandment." Jesus emphasized that obedience to God and future dealings with man solely involved love, love of God and love of man. Jesus was not just speaking to the Pharisees and the crowds of that time, he was speaking to us. So the question was not just simply answered, it was fully answered.
Isa 55:8 For my thoughts [are] not your thoughts, neither [are] your ways my ways, saith the LORD.
Isa 55:11 So shall my word be that goeth forth out of my mouth: it shall not return unto me void, but it shall accomplish that which I please, and it shall prosper [in the thing] whereto I sent it.