Let's not forget other verses such as:
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Mat_15:6 he need not honor his father.' So for the sake of your tradition you have made void the word of God.
Yet Jesus commands obedience to the Pharisees, and St. Paul commends some traditions.
So what gives?
There either exists a contradiction or a paradox. Since God's word cannot contradict Itself, these statements must be paradoxical.
The solution is that two kinds of traditions exist, Sacred Tradition and human tradition.
St. Paul commends Sacred Tradition, as did Jesus,
Then spake Jesus to the multitude, and to his disciples, Saying The scribes and the Pharisees sit in Moses' seat: "All therefore whatsoever they bid you observe, that observe and do; but do not ye after their works: for they say, and do not."
For the decision of their Scribes, or "Soferim" (Josephus, σοπισταί; N. T., γραμματεἴς), consisting originally of Aaronites, Levites, and common Israelites, they claimed the same authority as for the Biblical law, even in case of error (Sifre, Deut. 153-154); they endowed them with the power to abrogate the Law at times (see Abrogation of Laws), and they went so far as to say that he who transgressed their words deserved death (Ber. 4a). - http://www.jewishencyclopedia.com/articles/12087-pharisees
And the tradition that the Lord condemned was not the manifest established oral word of God (2Ths. 2:13) which would be written down, as was the norm, being in conformity to that which was written, (Acts 17:11) but were mere unwarranted traditions which were made doctrines, and some even were contrary to Scripture, (Mk. 7:2-16)
But as Rome does, the Pharisees could and did claim these were Scriptural, rejecting proof from Scripture to the contrary, as they presumed a level of veracity above what Scripture affords men.
An argument is made that equates authority with assured veracity, but while Scripture enjoins obedience to the powers that be, ecclesiastical or civil, (Dt. 17:8-13; Rm. 13:1-7; Heb. 13:17) it also nowhere teaches that an office of men is assuredly infallible whenever it universally speaks on faith and morals, but teaches that obedience to men is conditional upon conformity with the word of God, which Scripture assuredly is, and the conscience of the believer.
While the appeal to an infallible authority is attractive in that it precludes any dissenter as being correct, and thus unity is attained by implicit assent to it insomuch as it has defined things thusly, yet this is not how truth was preserved in Scripture, nor how the church began.
For while under the Roman model dissent from the magisterium is fatal, yet the church began in dissent from those who sat in the seat of Moses, with the Lord reproving them by Scripture and establishing his own claims upon Scriptural substantiation.
Thus the issue is how is truth established? By an infallible magisterium, or by holding Scripture as the standard for obedience and testing truth claims, which it is abundantly evidenced to be? And which provides for the office of the magisterium, yet not as assuredly infallible, but requires the church to continually uphold authority by manifestation of the truth in word and in power, as the kingdom of is of such, not in self declaration of the church being infallible.