My primary reason to think this is possible is because there would have had to be more dinosaurs than insects here today to render down to oil in the quantity we have already consumed.
In my opinion, the aboitic oil theory is not possible for many reasons.
First it is not dinosaurs, but algae, plankton and other items. The sedimentary basins where oil/gas is found is from time periods when it was underwater. Usually oceans but some freshwater as well. If you squeeze algae you get oil out of it. If you trap it in sediment without oxygen, squeeze and cook it for millions of years, you get oil/gas.
People tend to forget the earth changes in the time frame of hundreds of millions of years. No commercial oil/gas operation is outside of sedimentary basins. No oil/gas sources are ever found in igneous rocks which is pushed up from below.
Places like Hawaii that have very little sedimentation and lots of igneous rock pushed up from below have essentially no oil/gas.
Oil/gas is often found in layers trapped by a sealing cap rock. Depending on the geological conditions at the time this sediment is laid down, the resulting porosity and permeability of the rock changes. If it is coming up from the bottom, how does it get past the sealing rock below? That is what holds the oil/gas in place, otherwise it wouldn’t be in those layers.
Some question the depths. But 3 centimeters every thousand years adds ups to miles over hundreds of millions of years.
Combine that info with the fact we use heat and pressure to break down oil into smaller, simpler molecules. This is consistent with the fact that older, more thermally mature oil/gas fields tend to be more gas than oil.