The guillotine splitter is still used globally where the real quality paver jobs are installed. They are even used on 20 acre installations for work around light and utility poles.
For unit interlocking pavers concrete pavers, the real paving contractors use several guillotine type pavers because they are handy, reduce labor and produce a good edge, especially if the edge restraint in in place. - No getting up, measuring and moving things around when the paver is going to be installed against the edge restraint with a sand required between the paver end and the restraint before vibration.
On larger free-form projects (parking, long curved driveways, etc.) many contractors lay the pavers, mark them and saw with a gas powered saw (freehand) and then set the edge restraint before sanding and vibrating.
Some paver patterns (spirals and herring bones) require saw cuts, especially if it is a cosmetic effect, even though the function does not require it.
You can easily rent guillotines for longer periods from a real paver installer, but because of the flexibility, it usually is cheaper to have one handy for other jobs.
The use on tile and cultured stone is a smaller and unique application and usually requires different techniques to do it right.