An interesting question was posed to Rav Nissim Karelitz by representatives of the 'Hidabroot' organization.

They asked if someone donates to the organization to sponsor the day's electricity in memory of a yahrtzeit, does that count as having lit a 'ner neshama' so they won't have to go light their own candle, or should they still light a candle separately?

Rav Karelitz's answer is described as "surprising", and it is definitely interesting. Rav Karelitz answered that if one donates to sponsor the electricity for an organization that brings hundreds of thousands of Jews closer to Judaism and spreads Torah, that is the same thing as lighting a 'ner neshama', a candle in memory of the deceased, and surely the neshama benefits greatly from such a donation..
(source: Kooker, though I would note that the included image by the article has nothing to do with the article and is probably an error)

While I don't know why giving a donation would stop one from also lighting a candle, I would even venture to say that the donation is an actual mitzva while lighting the candle is only a minhag. Ergo, the donation should not be equal to the candle, but it should be considered far greater. But, again, what's the big deal to also light the candle?