Yep. Half the world's finances still spin on CSVs and FTP (no, not SFTP, FTP) If your customers request a format, that's the format you're using.

And if they don't request a format (or if you ask, and the response is "what's a format"), you need to use one that's 99.99% supported.

im okay with that. That being said, I have not had a single issue delivering zip files with lzma, and i KNOW that I have gotten MANY from the random sources.

I would also expect people to be able to decode h265 in an mp4 file.

Your proposal seems, to word it bluntly, retarded. You would have mp4 frozen for h264 for ETERNITY, and then invent a new format as replacement? or you would just say "god has bestowed upon the world h264, and it shall be the LAST CODEC EVER!".

get with the program. Things change, you cannot expect to be forwards compatible for ever. Sometimes people have to switch to newer versions of software.

It depends on your priorities.

If your customer is stuck in the 90s because his 90s technology works perfectly fine and he has no intention to fix things that are not broken. Then deliver stuff that is compatible with 90s technology. He will be happy, will continue to work with you and you will make money.

If your customer is using the latest technologies and values size efficiency, then use the latest codecs.

I usually default to being conservative, because those who are up to date usually don't have a problem with bigger files, but those who are not are going to have a problem with recent formats. Maybe overly so, but that's my experience with working with big companies with decades long lifecycles.

Your job is not to lecture your customer, unless he asked for it. And if he asked for it, he probably expects better arguments that "update your software, idiot". Your job is to deliver what works for him. Now, of course, it is your right to be picky and leave money on the table, I will be happy to go after you and take it.

not everything is a client<->customer relationship.

Professionally I can definitely support old stuff. It costs extra most often.

Conservative doesnt have to be stuck. I am not recommending we send h266 to everyone now, but h265 is well supported, as is AV1.

lzma support in zip has been widely supported for many years at this point. I am going to be choosing my "sane defaults", and if someone has a problem with that, they can simply do what they need to do to open it, or provide a damn good reason for me to go out of my way.