To avoid reflections which mess the signal unreadable matched load is needed at the receiving end of the line.Bidirectional (=half duplex only, no more than one talker at a time) traffic needs matched load at the both ends of the line.
The receiver in the RS422 or RS485 IC doesn't be the needed load, the voltage sensing circuit takes very little current from the line, right size resistor is needed.
One cannot insert many resistors because in parallel they are together much less than the matched load.
The matched load cannot be in the middle of the line because the resistor and the rest of the line together are an unmatched load.
If you have a long line and several receivers along the line, put the load to the end of the line at the input of the last receiver. The life of the coming wave is terminated in the resistor. Intermediate receivers only sniff the voltage as the wave passes them.
If you have an idea to have an Y branched cable where all three branches are longer than a couple of centimeters and there's a transmitter elsewhere than at the joint, forget it! There's no easy way to prevent fatal reflections in the joint when the signal comes from one of the branches.
=> The diagram multipoint solution is valid only if there's one cable with tranceivers at the ends with proper resistors, total two 100 Ohm resistors. In addition there's intermediate tranceivers which are connected to the cable with max a couple of centimeters long wires. Longer branches cause reflections. There's no strict limit how long branched wires can be tolerated, the mismatch increases gradually as the branches get longer. Inserting resistors to the intermediate tranceivers will mess the system totally.