The Law of Moses has not been abolished, because heaven and earth has not yet passed away, hence "unit heaven and earth pass away, not one jot or tittle will pass away from the Law..." and "whoever sets aside the least of the commands, will be called least...". Even Paul says, "we do not nullify the Law by this faith, but we uphold the Law". Let's start a discussion on these matters.
Read Acts 15, Ephesians 2:13-15, II Corinthians 3, Hebrews 7-8, Romans 7:1-6, Galatians 3-4. These Scriptures indicate the Mosaic Covenant and Law is not in effect anymore as a whole. This does not mean that the Mosaic Covenant or Law does not contain valuable spiritual and moral principles, though.
Notice the temporary nature that is portrayed in Galatians 3-4 concerning the Mosaic Covenant or law. Paul gave the example of the law being a tutor who raises and instructs a child until adulthood. Galatians 3 says that the Mosaic Covenant was in effect "until the seed came", with the seed being Jesus. Note particularly Galatians 3:25.
Additionally, we know that animal sacrifices and the Levitical priesthood are no longer in effect, so if your claim is that Matthew 5:17-19 means the Mosaic Covenant or law is in effect, you need to account for this. It says "not one jot or tittle"..therefore if you are saying that means the Mosaic Covenant is still in effect, you have a logical problem.
Usually what "Torah observers" mean is that days and meat laws need to be observed, and their observance of the Sabbath, holidays, and clean meat laws somehow makes them better than other Christians, or more doctrinally correct. There are obvious Scriptures in the New Testament after the crucifixion that indicate otherwise, particularly Colossians 2:16-17 and Romans 14.
As an ex "lawkeeper", I considered all non-observers in sin and unsaved due to their non-observance. It often creates a judgmental, exclusivist mentality. I am ashamed that I held that view, actually.
If anyone wants to discuss particular Scriptures one on one with me, and they are seriously concerned on this issue, I'd be glad to discuss them from my former observer perspective.
Note that many will claim that the phrase "law of Moses" doesn't mean the Mosaic Covenant, but some oral law or something. The "traditions of the elders" were indeed an issue in some of the encounters with Christ, but to claim that the above Scriptures refer to these traditions is in error. They are definitely referring to the Mosaic Covenant. You can discern this through simple reading of the texts. Also, study how the phrase "law of Moses" is used in the New Testament. Paul uses the phrase to refer to the laws regarding not muzzling an ox while it treads out grain, which is contained in Deuteronomy in the restatement of the Mosaic Covenant. Their assertion is bogus. Importing a false context is a standard tactic of Judaizers.
I have no issue with individuals who want to observe Sabbath, annual festivals or clean meat laws, IF they don't claim others are in sin due to non-observance, and don't claim that observance is a requirement, condition, or necessary proof of salvation. These are meaningful shadows and types..as Jesus is our spiritual Rest that the Sabbath pointed to (Matthew 11:28-30).
And, many make that claim. Armstrongites, some Hebrew Roots and Messianic Jews, and Sabbathkeepers make claims concerning non-observers being in sin. Quite often they bolster their belief system with a false view of church history..a grand conspiracy theory about the evil Roman Catholic Church or Constantine causing Sabbath observance to be abandoned. It is universally accepted by credible sources that virtually no Christians were observing Sabbath by AD140, and the typical Sabbathkeeper assertion is bogus.