Tool holders are, pun possibly intended, on the cutting edge of technology. Tool holders may also be designed to introduce additional properties to the cutting action, such as angular approach, spring loading, variable overhand and rigidity. They also ensure safety to the users and certainly have changed the way work has been carried out.
One of the earliest machine tools was a screw cutting lathe dating to about 1483, which utilized direct mechanical control of the cutting tool path. Tool presetters work in the same way. They help and provide assistance where other tools cannot, and provide stability to the people who have to use them.
A form tool is precision ground into a pattern that resembles the part to be formed. This can help speed things along and is another reason why tool holders are helpful. Another thing that is interesting is that on long running jobs it is common to use a roughing tool to remove the bulk of the material and reduce wear on the form too. This is interesting because of the correlation between most of these tools.
The toolpost is the part of a metalworking lathe which either holds the tool bit directly or holds a toolholder which contains the tool bit. Since all of these are able to work together, the productivity of workers has certainly increased, as has the safety and efficiency of most work that requires tools such as these.