Decoupling
What Is Decoupling? Datasheets and application notes for ICs typically specify ratings and placement for "decoupling capacitors". Decoupling is low-pass filtering.  A capacitor is not a filter, it is the shunt part of a low pass filter. Resistance or inductance (or both) in series is required to make a filter network with a capacitor.
Decoupling in the Early Days of Digital Integrated Circuits Many early logic boards were wire-wrap construction with IC socket power and ground pins daisy chained together with tiny wires. The inductance of these power and ground wires together with the "decoupling capacitors" usually worked to mitigate ground bounce and some crosstalk.
Here is a 68000 Single Board Computer made in 2016 of similar construction.
Decoupling with Multilayer PCBs Now we often use multilayer PCBs with low impedance power and ground planes. Properly executed power and ground planes solve the crosstalk problems but other pitfalls remain. While IC specifications typically address the location and value for "decoupling capacitors" these specs ignore the filter function. The lower resistance and inductance of the planes raises the filter corner frequency and decrease the attenuation dramatically. Is this a problem?  Standard engineering answer: It depends. For a stand-alone digital board with a dedicated power supply, not connected to anything else, there may be no problem.
Why There Might be a Problem Modern CMOS logic ICs draw appreciable supply current when they switch output states due to shoot through-current and output current. If you only use the specified "decoupling capacitors" with your power and ground planes you will be able to see your IC switching noise on your DC power lines. Making "decoupling caps" bigger will have a small effect.  Adding a small high side series impedance to the capacitor will make it into a filter and  "kill the noise".
Advanced Decoupling for High Performance Minimizing high di/dt current transients in grounding systems is a key to high performance systems. This is accomplished with strategic use of appropriately specified and placed high side series impedances and shunt capacitors. Components receive the high di/dt component of their current draw from an adjacent capacitor instead of a remote source.
Ancient History - Decoupling in Vacuum Tube Circuits Filters for decoupling power supply feedback between stages were used in vacuum tube radios. In this 5 Tube Radio, V3 power is decoupled from V2 power by R2 and the right side of dual cap C1. When the electrolyte in C1 dries out and the 20uF side degrades enough, oscillation ensues. Often this sounded like a single cylinder outboard, hence it was called motorboating. R1 and the 40uF left side of C1 filter the half wave ripple from rectifier tube V1. When the left side of C1 degrades you get 60Hz hum in the speaker