[Nexus 6 Android Development] magnamentis:
1) The video explaining how to disable encryption is too long for the actual information needed. Just "format/wipe internal storage" is all that has to be said. NitrogenOS takes care of the rest.

the video is not "TOO" long, it's just longer than absolutely necessary to make sure that everyone can cope and there is either wipe data or format data, wipe data does not wipe internal storage hence format is the better recommendation to make sure that not half of the people wipe data and end up in a mess, if you made it your way that's ok but it's better to format, just to be on the safe side, some people who did as you suggest but forgot to include internal storage got into trouble, format is safe and no mistake can be made. since formatting is a twrp feature readily available to click, why making a big story around it? simply format and all is well, everything else needs explanation and agreement on terms with an error quota accordingly, makes no sense to go there really

2) that video recommends flashing a custom kernel - bad advice and unnecessary

this device has a had a kernel problem for more than a year, not that they were not working but for those who have the device from the beginning and know the difference there were small issues like read/write speed and many others, depending on kernel used on which API version. i won't list the entire bunch of issues that i got rid of with kernel tweaking because now we have back a top-kernel by franciso franco and everyone who will try it out can immediately see what i mean, finally we have a decent kernel again that makes the device perform like it once did with stock, elementalX and franco. popcorn for pie is ok with this rom but not for others, franco works across the board and perfect.

therefore you statement is not target leading for all users and makes false impression, keeping some from trying out what's best for them, hence it's jumping to conclusion based on your experience, free after the "MOTTO" what's best for me has to be good for everyone = not correct, not technically nor ethically

3) a previous post actually suggests formatting and wiping will give different results, so stick with format - that's false. I did a wipe, it worked fine.

for some users it provides different results due to the reasons described above, hence your statement is not correct = damaging for some

4) if the OP included 4 simple words "format/wipe internal storage" the number of confused posts would be significantly less.

whoever follows the OP's guidance will succeed, hence no reason to tell the dev what and how to do things

A non slotted device has not had encryption become a crippling issue for ROM installation in a long time.

this sentence is not comprehensive and encryption is not different on slotted or non-slotted devices, i have both kinds

and both behave the same when it comes to encryption

Many users opt to not wipe internal storage because its usually not an issue for most ROMs, and is easier.

that's true, the reason is "laziness" , not wanting to loose data, not wanting to make a backup first etc. and basing their doings on past experience or their own experience like you do, who doesn't decrypt which comes with total data loss pays the price, that's it, because it won't work, how exactly one gets his data partition formatted one can try out but following the tutorial in the video and in the OP works, everything else is superfluous

you made several attempts to tell us something that has mostly been discussed "ad nauseam" and resolved already, there was no need for that in the first case, it feels like insisting on something and since not all is correct that's not a good move IMO

everyone who is reading the OP, watching the video and reading the first 20 pages of this thread will succeed, period.

since we finally have back a really perfect kernel again after a long time i recommend to try out franco kernel, try out means it remains your choice, not mandatory by far, but worth a try, you will see.