I'm 46, and people my age talk about leaving off earlier experience, so as not to look too old. I condensed my earlier experience (the first 10 years) into a couple sentences describing the roles--not to look younger, but because with an average stint of 2.5 years, there are just too many jobs to list.

Other steps people my age take are to stop listing dates--either select dates like university graduation, or--in extreme cases--all employment dates.

Keep in mind that there are different biases at different screening points along the way. The manager with the open position may want someone older and more experienced, but the people recruiting, screening, and filtering the candidates may be biased or simply not familiar with the value of experience that doesn't match today's buzzwords.

I've got about 14 years of development experience and I also leave off some of my earlier experience on my resume. I do it not to conceal my age, but because the stuff I was doing 10 years ago is so much less interesting and relevant to my applications today.

Does my outlook not resonate with you/other older employees?

It does with me, but I'm less picky about traditional experience than most people. I'd prefer a list of technologies that someone knows, a list of things they want to work on, and a blurb about how they might fit in to the role I'm hiring for.

The cover letter seems to have fallen out of fashion, but I find a couple paragraphs of prose far more revealing about a person's abilities than a resume. Of course it's also more work to craft one for every position you're interested in, and doesn't help much if you're looking to put yourself into a database for recruiters (e.g. LinkedIn or any other job site), where they force you to iterate your experience in chronological order and list technologies with no context.

I think it's important to leave off things you're not interested in. I did Perl for years but there is no amount of money that would get me to do it again, so I minimize or eliminate its presence on my resume, and put extra emphasis on the technologies I want to work with now.

I have a business and tech background, I massage and prune experience and roles based on what type of position I'm applying for. Example my early years in sales and marketing are pretty irrelevant as a developer, my webGL experience does little to promote me as a business analyst

To be fair, the hiring signal you can get from a description of 25 years of experience is probably comparable to the signal you can get from a description of the most recent 5 or maybe 10 years of experience.

I hire with anonymous data. I would look at a statement like '25 years experience' on a CV and completely ignore it, as I have no idea how competant the candidate is based on this. I would look for the key technical words and impact statements in the CV to show depth of experience rather than general statements like this.

My god, "key technical words" and "impact statements". Those likely have a negative correlation with competency.

Competancy is assessed at interview, not at sift. The sift simply identifies that candidate meets the minimum possible spec for the role and can be interviewed. They may end up well exceeding the job spec after competancy based interview.