First, i like the idea, this gives people a better view but be carefull in reading and interpeting the traces.
On small correction, SRF is self resonant frequency ( see Agilents impedance measure handbook, network analysis from Siebel, RF design from Bowick, RF measurements from Terman, ect) not important in this case, because in this case we see a series resonance, but a coil has a SRF too and that is parallel resonance. I like the use of the right terms. ( to be complete, series and parallel resonance is there in two flavours, there is imaginaire resonance and Phase resonance ( see AC theory by D Knight for the math and more background)
Paralleling caps can serve serveral means, lowering ESR is one, but an electrolytic cap with for instance 100 nF is very normal ( just look at the avarage 78XX regulator) or look at all caps in a powerrail.
But to do this mindless is not good. You can get parallel resonance effects at the wrong frequency.
You see in the pictures if it is the right choise. Remember the working frequency is important, for a switcher you want good impedance at a high frequency but if it is for 100 Hz who cares ( most times) the cap is worthles at 100 KHz.
if your design works at 100 Hz the reactance at that frequency is important. But if there is a switcher near by at 100 KHz, or the emc caused by f.i. switching diodes is at some frequency where you do not want it, a small parallel cap with the right reactance at that frequency will maybe give a ugly ( negative) bump in your nice flat log/log sweep but if it is at the right frequency it is what you need (i use reactance but at the end the impedance is important too, but be carefull, if the impedance is high because of ESR instead of reactance ( because for instance, skin loss, dielectric loss instead of reactance you dissipate power instead of filtering, also ESL is lowering the capacitive reactance)
There are high speed designs where capacitors with their ESR and ESL also caused by vias and traces are tuned by vna to resonance to get the lowest possible impedance, or that value that gives you the right phase margin. So you have caps with high ESR, even with build in resistors.
I myself always use for (electrolitic and other) caps the following traces ( i can show 8 traces at on sweep and 6 frequency markers with data from all traces. so that makes it easy) Rs + jX , |Z|, Cs and phase. The phase to be sure I'm looking at real SRF and that makes it also easy to see calibration mistakes. For old caps I clean the legs first because if you are in tens of milliOhm area the resistance of oxide, thermal effects ( seebeck), humidity, dirty fingers, temperature but even a cell phone can influence measurements)
After the SRF the cap behaves inductive, that is also why i use phase and reactance too. Z is a scalar, you do not see the sign. Ok, if Z goes up after the lowest Z value the cap is probably becoming inductive. It is still X Ohm but if it is + jX it will have other effects as being -jX. But Z can go up and this dip is not allways the SRF. For instance the R part can drive the impedance more up as the ESL drives the reactance down. Z looks like SRF but in fact it is not there. You need to sweep Xc and phase to be sure.
Do not forget this are log/log sweeps, they look nice and flat. I rather use linear sweep. That gives me more information. On a log/log a line seems to be more flat but in reallity a straight line then represents a rather exponential behaviour. If you for instance measure the Diode Vf knee on a log/log scale you get a straight line ( see several articles of Bob pease)
However commercial they like to use log/log to give a huge range but for most because it looks better.
The origin was to get a bigger dynamic range. If you make a ( vertical) linear filter sweep you see only a small part of the stopband, lose details in the pass band if you want to fit the whole picture. But here we do not need a very high dynamic range, here log scales just hide details and make them nice and smooth. But making pretty linear sweeps can be challenging.