For a lot of people, the purpose of a funeral eulogy is to tell the life story.
Three problems here. First, it can sound very like a CV or a series of and-thens – “And then she moved to Felixstowe and found employment with JC Whittle & Sons where she…” This sort of narrative can be quite boring and predictable – not a good look for a story – and a lot of people will know all or most of it. Lots of very interesting and loveable people have led uneventful lives. Nothing wrong with that.
The second problem is that the storyline moves inexorably towards death. If you are celebrating the life, that’s not where you want to be heading.
The third problem is that it may give you too much to say, and you’ll have to gabble to fit it all in.
Having said which, there’s everything to be said for telling people things they didn’t know – so long as they interesting and illuminate the person who has died. For example, many people may not know much about the early years, when the person who died may have had – this is the important bit – important formative experiences.