The Peshitta is the standard Syriac Bible, and it is the reason the script matters far beyond the communities that use it. It is one of the oldest translations of the Christian scriptures, made from Hebrew and from Greek, and it is read in the Syriac churches to this day.
That gives Syriac manuscripts a particular kind of authority in textual scholarship. A translation made early is a witness to what its source said at the time it was made, so a Syriac reading can bear on a question about a Greek or Hebrew text. Syriac also preserves works whose originals are lost: early Christian writing that survives in this language and in no other, and Greek philosophy and medicine that reached Arabic through Syriac translators.
All of that rests on copies, and copies rest on legibility. A script in which two letters differ by a single dot, in which the earliest writing omits the dot, and in which the vowels are not written at all, is a script that puts weight on the reader and on the copyist. The pointing systems, the vowel marks and the careful hands of the manuscript tradition are the answer that was worked out to that problem over centuries.
Rish and dalath are the smallest and sharpest instance of it. Two letters, one shape, one dot, and behind the dot a difference between words. The whole apparatus of Syriac pointing begins there.