Warren Buffett is an incredibly successful investor and one of the richest people in the world. Focusing on value, fundamentals, and holding for the long term have been the hallmarks of his investing strategy. His company, Berkshire Hathaway, owns many top growth stocks, including tech giant Amazon.

However, one stock that you might not find there anytime soon is Teladoc Health (TDOC 0.26%). Although the business is growing and has significant potential, there are a couple of big reasons why it likely won't be in Berkshire's portfolio anytime soon.

Buffett values predictability

One of the things Buffett takes into consideration when investing in a stock is trying to predict how the business will do in 10 years. Naturally, that isn't easy.

Among his favorite stocks is soft drink giant Coca-Cola, which is stable and has established itself as a top global brand around the world. Its position in the marketplace is sound, because it has adapted to market trends over the years (e.g., becoming more health-conscious), and it's likely to continue doing that in the future.

Teladoc's future isn't predictable

With Teladoc, however, the future is much less certain. Telehealth skyrocketed in popularity during the early stage of the pandemic. Even now, as the economy has been returning to normal, Teladoc has been growing its virtual visits -- they hit just about 4.7 million for the period ended June 30 and are up 28% year over year.

But how long that growth continues is less certain. It acquired chronic care company Livongo a few years ago in the hopes that it would significantly expand its business. And although it is able to reach more customers, the growth rate has still been slowing down.

TDOC Revenue (Quarterly YOY Growth) Chart.

TDOC Revenue (Quarterly YOY Growth) data by YCharts.

Teladoc even wrote down $6.6 billion on the transaction earlier this year in what has turned out to be a gross miscalculation of its value.

Last month, the House passed the Advancing Telehealth Beyond COVID-19 Act, which will extend waivers so that Medicare will continue to reimburse people for telehealth use up until December 2024. Given that telehealth could be a low-cost alternative to traditional primary care, it seems plausible that reimbursements will continue -- but it isn't a guarantee.

The business doesn't have a wide moat

A moat, a wide competitive advantage, is another key feature that Buffett desires from his stocks. Although Teladoc is the big name in telehealth today, that may not be the case in the future. Many companies offer telehealth services, including CVS Health and Cigna, and even Amazon has launched its own service nationwide this year. 

The challenge for Buffett and other long-term investors is knowing which brand will reign supreme in 10 years. It may be Teladoc, but it could also be a company that's not in the space today. After all, the service primarily depends on videoconferencing capabilities, which businesses have been using for years. 

Why Teladoc is still a good, long-term buy

Buffett will often miss out on investments if they're out of his circle of competence. He invests in businesses he can understand easily and are predictable. Teladoc's business isn't overly complex, but its future is difficult to predict, and the lack of moat doesn't help either. But the stock itself can still be successful.

Take Amazon, for example. Although it is in Berkshire's portfolio today, it's a relatively small holding and one that was added just a few years ago. Buffett previously stated, "I had no idea that it had the potential. I blew it."

Teladoc hasn't been a stock that he's missed out on today -- its shares have collapsed 75% in the span of just one year (the S&P 500 has declined just 6% during that time frame). However, many investors are also heavily betting against the healthcare stock -- its short interest as a percentage of float was 23% as of July 15.

Teladoc is still growing and has significant potential (despite the uncertainty) as it can allow doctors to be more efficient and reach more patients than primary care. Buffett may never invest, but that doesn't mean it won't be successful. Its growth prospects are appealing, and that's why I believe it would be a mistake to give up on the stock right now