As I said, there is very rarely a reason to NEED to search for a poster.
When you post on a thread, it goes into your 'threads I'm watching.'
If you don't post on it/don't want to post on it, you can click 'watch this thread.'
So you can ALWAYS return to any particular thread, very easily.
In the vast majority of cases, people looking through a poster's posting history is not doing it with good intentions. Indeed, they will almost always be doing it for nefarious reasons.
I am very suspicious of ANYONE who is desperate to have the 'search for a poster' function restored. Especially the ones saying 'I may as well not BE here if I can't look at peoples posting history.' I mean WTAF? 
Trying to catch people out, and looking for something to throw in their face to make yourself look clever, is the reason for snooping though a poster's search history in the VAST MAJORITY of cases. (Probably at least 95% of them actually.)
As has been said before, many people will have consistencies in various threads, because many people don't want to be recognised.
And you don't need it to look for any threads of your OWN threads. They are in your 'threads I started' FGS.