This avoids the problems with terminal accuracy normally seen by command guided missiles, especially at long range.
Typically two radars are used, one tracking the target and another the missile, so that they can fly independent and widely separated paths.
There are a number of minor issues that result in a maximum accuracy (for early designs) on the order of tens of meters, but this is independent of range.
For SAMs in high-traffic environments, especially ships facing salvos of anti-ship missiles, it is possible to overwhelm the system's capabilities.
In theory, the missile can add electronics to allow it to continue tracking a non-continuous signal and thus allow a single radar to provide tracking to several missiles, but using electronics of the 1950s and 60s this would be prohibitively expensive and large; even command guided systems generally lacked this capability.
TVM solves the accuracy problem of command guidance, but not the issue of requiring separate radars.
Centralizing this at the launcher site is a much more tractable problem, especially after the introduction of military-grade transistors in the later 1950s.
It is also possible for the ground station to receive direct radar reflections from the target (rather than the data downloaded by the missile) and combine the two sources of information to generate the interception course.
For example, the data link could potentially be jammed, which is not possible with an active homing or “fire and forget” missile.