In the days of party lines, 2, 4, 6, or 8 users were commonly connected on the same pair which appeared at several different locations.
A bridge tap has no hybrid coil or other impedance matching components, just a “T” (or branch) in the cable.
Both the tap and its unterminated branch cause unwanted signal reflections, also called echoes.
The echoed signal is now out of phase and mixed with the original, creating, among other impairments, attenuation distortion.
Line in bridge tap technology can be much less performing caused to the high attenuation added and to the length of the cable itself.