Re: Worrying trend
"no dedicated field to enter a customer purchase order on an invoice"
This can be worked around on *most* systems That 'I' am aware of ... BUT a work around is NOT good enough really, particularly if you are paying an ongoing fee for support/updates/etc.
You MAY forgive it on a package you paid for ONCE, some years ago, but ongoing subscription type systems are supposed to be an advantage BECAUSE there is on-going support and fixes.
Too many people/companies THINK they can write an accounting package/system ... it is not trivial and NEEDS input from real accountants who use these systems in anger in real companies.
People who think they 'know how' make these sorts of mistakes because they do not use accounts for REAL and have to deal with large amounts of customers daily.
A 'big system 'can be scaled down BUT a 'small system' does not ALWAYS scale up ... (I'm teaching grandma to suck eggs at this point !!!)
P.S.
I saw these problems over 30 years ago and they STILL apply now ... sigh!!! ... nothing learnt & nothing changes !!!
:)