Is transistor the only electronic component on a CPU?
The logical blocks and memories can be made out of only transistors.  The important question is: are all of the circuits on CPUs logical blocks and memories, or is there anything else?  

The answer is, there are always some other circuits.  Here are some examples:


ESD protection circuits often uses diodes and resistors
Internal bypass capacitors: actually these can be made just from transistor gates, but they are often also made in the metal layers.
Analog blocks like internal LDO regulators, bandgap references, power-on-reset comparators, etc. are usually best implemented with some resistors among the transistors. It may be possible to get rid of the resistors and use 100% transistors in some of these cases, but it's not necessarily optimal.
Internal oscillators may use inductor-capacitor (LC) tank circuits (though inductors are so large that they are not cost-effective on modern general purpose CPUs).
Etc., etc.